P-Q

packet

See network.

password

See authentication.

patch

See release.

patent

See intellectual property.

path-dependent effects

In economics, the influence of accumulated past investments and management decisions on current circumstances, as distinct from a hypothetical situation that might result from starting from scratch.

peer-to-peer

See client-server.

performance

Metrics measuring aspects of speed for software and its environment. Throughput is a measure of what is accomplished per unit time, in terms of processing tasks or data stored, retrieved, or communicated. Capacity is the ideal throughput of a resource (processing, storage, or communication) if fully utilized at all times. Utilization is the actual throughput as a fraction of capacity (a number between 0 and 1). Delay is a measure of the time elapsing between when an action is requested and when it is completed in its entirety. An extreme form of delay is loss, when an action is not completed soon enough to be of use.

pervasive computing

Computing and software embedded into many everyday products, scattered pervasively in our environment, and networked to enable those products to interact to provide new capabilities.

plaintext

See cryptography.

platform

A set of infrastructure equipment and software that is widely deployed and assumed available to support a given software distribution (possibly with complementary software that provides an environment for the distribution).

policy

A plan or course of action guiding individuals, organizations, or governments. In computing, a prescribed set of actions or restrictions on actions that plays an important role in security and system administration.

portability

Describes a software distribution that can successfully execute with full functionality on different platforms. This requires portable execution (ability to run on processors with different instruction sets, enabled by a virtual machine) and an environment that appears to the program to be the same on each platform. The virtual machine is an interpreter (layered on the operating system) for the object code instruction set assumed within the distribution. It is also possible to compile that object code into the native instruction set of the processor the first time the software is executed using a just-in-time compiler. Alternatively, compilation can be performed at the time of deployment or installation. Portable software supports mobile code, in which software is distributed by dynamically downloading and executing without requiring a manual installation step.

presentation

See client-server.

price

In economics, what is charged for a product or service. Price discrimination occurs when the difference between price and marginal cost is different for different customers. One form of price discrimination is versioning, a strategy of providing distinct versions (or variants) of a product at different prices. Value pricing emphasizes willingness to pay rather than supplier cost, and requires price discrimination. A common approximation to value pricing is usage-based pricing (based on the number of users, the time they use the software, the payment per use, the number and performance of processors executing the software, and so on). Another distinction is between fixed payments for each upgrade or recurring subscription payments.

price discrimination

See price.

privacy

The ability of a user to share personal information for legitimate purposes while maintaining control over its dissemination to third parties.

process

A sequence of steps executed over and over to achieve some high-level ongoing need. A business process starts with material and various resources (e.g., workers, space) and ends with a product or service for customers. In an operating system, a process is an abstract environment for execution of a single software program.

processing

One of three supporting information technologies, it modifies digital information under control of software during the execution of that software. A processor has a defined instruction set (list of atomic actions the processor is prepared to execute on behalf of the program). A program expressed in terms of this instruction set is called native object code. Source code can be translated into this native object code in one stage or more than one stage (creating intermediate forms of object code using different instruction sets). A compiler does a one-time translation of source code to object code, or the source code (or intermediate object code) can be directly executed on the fly by an interpreter.

protocol

See module.

prototype

A software implementation that is not yet a distribution; that is, it demonstrates features and capabilities with sufficient fidelity for experimentation and feedback but is not ready for provisioning and operations in a production environment.

provisioning

Undertaken by a human organization after development and before operations, all the steps needed to acquire, integrate, and test software within its future operational context. Includes planning, training future operators and users, and taking into account human, organizational, and technological elements of the future operational context.

public key infrastructure (PKI)

See digital certificate.

quality of service (QOS)

For a service provider, performance objectives or guarantees that can be configured by appropriate resource allocations. A service-level agreement (SLA) between provider and customer lays out promises for QOS.