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Packet is the term for a unit of packaged data used for network communications. Protocols such as TCP/IP use packets to send and receive information. Each packet is separate from another and can be reassembled when reaching the source. The TCP packet is sent bundled the IP packet that has the network address. TCP packets have header information with the data that includes source and destination information, checksum error detection and condition flags. Unless the data is encrypted a packet sniffer could see all packets in network communications clearly.
Packet sniffers are hardware devices or software utilities that grabs packets off a network or Internet from a designated IP address. This address could be from a router, gateway, web site, or a computer system. Packet sniffers are used to monitor and collect data about network communications. Unless the data is encrypted a sniffer could see all network communications clearly.
Packet switching is the method used to move data around on a network or the Internet. In packet switching all the data coming out of a computer is broken up into pieces, sorted, addressed and then sent along possibly different routes to the same destination. This allows multiple users access to the same line at the same time without packet collisions.
Page down key refers to a key on the keyboard that says Page Down or PG DN on it. It is a directional key that initiates cursor movement on the screen.
Page up key refers to a key on the keyboard that says Page Up or PG UP on it. It is a directional key that initiates cursor movement on the screen.
Parallel ports are hardware ports on a computer system. These physical ports support synchronous data flow to peripheral devices. Printers usually use connected with parallel cables to parallel ports.
Parity bits are used in asynchronous communications and data storage where an extra parity bit is added for parity checking.
Parity checking is a technique for checking errors in data communications by looking at parity bits and data storage. It entails adding the number of bits per data bytes to detect errors.
Parking a hard drive disables the read head so it does not move at all. This makes the computer safer to physically transport.
Parsing text breaks a long string of text into individual smaller strings when they are separated by a recognized delimiter.
Partitions are sections of a drive such as a hard drive that has been formatted separately. A formatted partition can be allocated with a drive letter or can be mounted as a separate drive by the operating system.
Passwords are secret set of characters given to a computer user to access a computer system or network. A combination of username and password can be requested by the operating system to login to the computer as a security measure. Both the username and password are normally case sensitive. A password usually has to be over 8 characters. A password that would be difficult to crack would be one that uses a combination of special characters number and letters. A bad password is one that would be easily guessed or uses plain words from the dictionary.
Pasting in computer terms refers to the act of retrieving a file or an object within a file from the temporary storage area, sometimes called the clipboard. After an object or file has been cut or copied it can be pasted somewhere else at any time. Usually only one item can be stored at a time in the temporary storage area. It stays there until another item replaces it. Paste is part of the three ubiquitous editing tools, copy, cut and paste.
Patch is a term for a quick fix that may be supplied for a problem to software that contains a known bug.
Path refers to the directory address of a file as corresponding to the directory tree on a computer system. The entire path of the file can include the drive letter, a colon, a backslash, the directory path and the file name. On some operating systems the path starts instead with a forward slash indicating the root directory. Sometimes the entire path has to be given before the system recognizes the file.
PC stands for Personal Computer which is a computer system made for home users that term became popularized by the media in the earlier 1980s.
PCI stands for Protocol Control Information. The PCI is protocol information from the OSI network model added by an OSI entity to the data passed down from the layer above forming a Protocol Data Unit.
PCMCIA stands for Personal Computer Memory Card International Association. They provide a standard for expansion cards used on laptop computers.
PDF stands for the Portable Document Format. This is a proprietary format for documents that is platform independent. It is designed to enable the user to view or print the documents regardless of the operating system used. The files usually have a dot PDF extension. They can be viewed through a document reader program provided free on the Internet.
PDU stands for Protocol Data Unit. This is OSI terminology for a TCP/IP packet. A PDU is a data object exchanged by protocols within a given layer. PDUs consist of both Protocol Control Information and user data.
Peer is the term for an end system on a peer to peer network model. This type of model does not have a central server, but consists of interconnected equivalent workstation computers working as peers.
Peer to peer is a network model for a local access network that does not have a central server but consist of interconnected equivalent workstation computers working as peers. On a peer to peer network every computer system has access to the public files of the other computers on the network.
Peripherals are hardware devices that extend outside the computer case, but are connected to and controlled by a computer system. Usually a peripheral device needs a software driver installed on the computer system before the device will be recognized. Anything outside the case can be considered Examples of peripheral devices are printers, cameras, speakers, mice and keyboards.
Perl is a flexible open source programming language. Perl can be run as a compiled program, run as a scripting language, or run from the command line. On the web this language can be interpreted at run time on the web server. Created and maintained by a community of programmers on the Internet Perl has a number of resources and modules available. Perl is platform independent running on most any computer.
Permissions are pieces of code stored with a file that contain information pertaining to ownership and read and write permissions to the file. Permissions are similar to file attributes.
PGP stands for Pretty Good Privacy. This is an encryption standard for sending secure emails and other Internet communications.
Phishing is technology for the sending out of emails trying to trick the recipient into sending secure information like financial information or passwords by filling out a form or sending a reply email. The sender usually tries to mimic a trusted company with the email or with a web site linked to the email.
Physical drive refers to an actual hard drive that is connected physically to the computer hardware. A virtual drive, as opposed to a physical drive, is a partition of a physical drive.
Physical layer refers to a layer in the seven layer OSI network model that provides the means to activate and use physical connections for bit transmission. The physical layer provides the procedures for transferring a single bit across physical media of a network.
Physical media refers to any means in the physical connection for transferring signals between OSI systems. Considered to be outside the OSI network model, the media described can is at the bottom of the physical layer.
Picosecond is one trillionth of a second. Processor speed and RAM chips can be measured in picoseconds. A picosecond is a thousandth of a nanosecond. It is sometimes abbreviated by the letters ps.
PING is an acronym for a Packet INternet Groper. Ping is a simple program used to test reachability of a IP destination by sending an ICMP echo request packet to the network address and waiting for a reply. The term can be used as a verb as in to ping the server to see if it is up. PING is distinct from the image format PNG, also pronounced ping.
Pixels are the smallest element of a screen display. Each monitor screen has millions of pixels that combine to create the display for the user.
Platform refers to the overall hardware or software architecture for a computer system, operating system or network. The term platform alone usually just refers to the operating system that is being used on a particular computer. Certain devices and programs created for one platform may not work with other platforms unless they are platform independent.
Platform independent indicates that the program or hardware device will work on different operating systems or on other different platform architectures.
Plug and play refers to hardware devices are recognized by computers when installed. Hardware platforms and operating system platforms have devices that might not work with them. If the device is plug and play and the platform is supported, then the device and the device drivers should be recognized by the system and the drivers should be easier to install.
Plug-ins are add on software for a larger software application that extend a program such as a web browser. Plug-ins for web browser include multimedia movie players which can enhance a web site.
PNG is an acronym for Portable Network Graphics. Pronounced ping this format is a nonproprietary supported by the W3C by made as a possible replacement for the other two popular formats that are arguably proprietary. It has been historically a less popular format than the other two. GIF, JPEG and PNG are currently all used freely and openly on the web. PNG files usually have the extension dot PNG at the end of the file name. This is a different ping than the network ping command which is pronounced the same.
Pointer refers to the representation of the current relative position of the mouse on the screen. The mouse pointer usually defaults as an arrow. The tip of the arrow is where the mouse will click when the mouse button is pressed.
POP and POP3 are acronyms for Post Office Protocols. These protocols are used by an email server on networks or the Internet to provide a pick up point for delivering email to a computer. They can be used in conjunction with the SMTP protocol to provide a user with email services.
Port refers to different things depending on the context of usage. In hardware a port can refer to a physical connector or outlet used to attach a hardware device. A parallel port and communication port are available for peripheral devices such as printers. In software a port refers to an address between two items. Specifically, an HTTP port is used in TCP/IP as part of the Internet address where each port is associated with a service. Port is also the name of the mechanism that governs data flow to the CPU.
Portal usually is used as a term to described a point of entry web site that is or is intended to be an entrance for browsing the web. A portal web site may also offer exclusive services to entice users.
Porting in programming terms mean to compile a program or a software application so it runs on a different platform.
Posting refers to different things depending on the context of usage. In network terminology it refers to placing a single message into a network communications system. On a newsgroup posting is entering a message that can be seen by other members.
POSI stands for Promoting OSI. This conference for Japanese executives set policies and commit resources promoting OSI standards in Japan.
Power supplies are anything that supplies electricity to a computer. In PCs they are the internal hardware power units that are the source of electricity to the computer hardware components, such as the motherboard and all the drives. It converts the AC current from the power cord to DC current for the computer system to use. There are two basic types of power supplies in personal computers the older AT models and newer ATX models provide automatic shut off.
Power surges are a threat to a computer system because they can harm hardware components. The proper use of a good surge protector can help alleviate the threat from power surges. Power surges come through the local electrical utilities from things like blown transformers and lightening strikes.
PPP stands for Point to Point Protocol. It is a network protocol that works on the transport layer and data link layer in the OSI network model. It is used for transporting TCP/IP protocols over a network much like SLIP. PPP can transport virtually any protocols over a network using a start and stop sequence over serial lines. This successor to SLIP provides router-to-router and host-to-network connections over both synchronous and asynchronous circuits.
Presentation address is used in the OSI network model is the address on a network used to locate an OSI application entity.
Presentation layer refers to the OSI network model layer that determines how application information is represented while being sent between two end systems connected to a network.
Private keys are generated numeric data used in encryption formulas to decrypt messages. They are kept private because they are necessary for the user to decrypt and encrypt messages. Private keys in conjunction with public keys are used to exchange encrypted messages using the public key encryption model.
PRMD stands for PRivate Management Domain. This is a message handling system for organization of email.
Process is the term for the execution of program instructions by the CPU microprocessor A processor can execute a process once or it can be ongoing process such as a service.
Processors are chips with integrated circuits that contain the logic and the control units for analyzing data on a computer.
Program is the term for a computer software application. It is called a computer program because it is constructed with programming. All software applications need an executable file to start a program.
Programmers are people who write software code to create computer programs or software applications by using a programming language.
Programming a software application is the act of writing the computer code following the syntax of a certain language programing. Programming is combined with other steps that include software testing and debugging.
Programming languages are artificially created languages, not natural languages, constructed of a set of vocabulary and rules called the programming syntax that are used to create programs and software applications.
PROM is an acronym for Programmable Read-Only Memory. It is a type of ROM memory chip that can be designated for a certain use.
Prompts are on screen command line symbols, characters or phrases that indicates that the computer system is ready for input from the user.
Protocols
are rule sets used on a network to facilitate
communications by giving a formal description of rules to be followed.
On the Internet the low level protocols
are TCP and IP
from the TCP/IP suite. The higher level
Proxy refers to situation whereby one computer system fronts as a proxy for another system in responding to protocol requests. Proxy systems are used in networks to avoid having to implement full protocol stacks in simple network devices.
Proxy ARPs are the technique in which one device works as a router on a network to provide IP address resolution for a computer. The address resolution protocol requests intended for the computer systems are intercepted by the proxy ARP device by faking its identity. The router accepts responsibility for routing packets to the system. Proxy ARP can allow a server to use a single IP address for two physical networks. Subnetworking is another solution to address resolution.
Proxy servers are intermediary computer system located between a client computer and a server computer on a network. Proxy servers can be connected to a network or the Internet. A proxy server is as an intermediary system connected to the Internet. It can work as an HTTP server to an end system. It gives the client computer access to the Internet with less security risk. The client makes all of its protocol requests to the proxy server, which then makes requests to the true server and passes the results back to the client.
PSN stands for Packet Switch Node. The term used for switching packets on certain nodes implemented in computers used for the ARPANET and MILNET networks. These packets used to be called Interface Message Processors.
Public key is a number generated from numeric data used in encryption formulas to encrypt messages. They are made available to everyone because the are needed for others to decipher and encrypt messages from the user. Public keys in conjunction with private keys are used to exchange encrypted messages using the public key encryption model.
Public key encryption refers to an encryption model using generated numeric data and encryption algorithms to encrypt messages sent over public networks such as the Internet. Two keys are used, a public key and a private key. Public keys in conjunction with private keys can be used to exchange encoded messages using this public key encryption model. PGP is an encryption standard that is available on the Internet and uses the public key encryption model.
Python is an interpreted interactive programming language that is used on many web servers. It is an object-oriented programming language with many built-in modules that is comparable to Perl or Java. Python is portable and can be used for software application development on almost any computer.
