{{about, a technical topic, project management, software development process Program lifecycle phases are the stages a

computer program A computer program is a sequence or set of instructions in a programming language for a computer to Execution (computing), execute. It is one component of software, which also includes software documentation, documentation and other intangibl ...

undergoes, from initial creation to deployment and

execution Capital punishment, also known as the death penalty and formerly called judicial homicide, is the state-sanctioned killing of a person as punishment for actual or supposed misconduct. The sentence ordering that an offender be punished in ...

. The phases are edit time, compile time, link time, distribution time, installation time, load time, and run time. Lifecycle phases do not necessarily happen in a linear order, and they can be intertwined in various ways. For example, when modifying a program,

software developer Software development is the process of designing and Implementation, implementing a software solution to Computer user satisfaction, satisfy a User (computing), user. The process is more encompassing than Computer programming, programming, wri ...

s may need to repeatedly edit, compile, install, and execute it on their own computers to ensure sufficient quality before it can be distributed to users; copies of the modified program are then downloaded, installed, and executed by users on their computers.

Phases

Edit time is when the

source code In computing, source code, or simply code or source, is a plain text computer program written in a programming language. A programmer writes the human readable source code to control the behavior of a computer. Since a computer, at base, only ...

of the program is being edited. This spans initial creation to any bug fix, refactoring, or addition of new features. Editing is typically performed by a person, but automated

design tool Design tools are objects, media, or computer programs, which can be used to design. They may influence the process of production, expression and perception of design ideas and therefore need to be applied skillfully. Objects New ideas can com ...

s and

metaprogramming Metaprogramming is a computer programming technique in which computer programs have the ability to treat other programs as their data. It means that a program can be designed to read, generate, analyse, or transform other programs, and even modi ...

systems may also be used.

Compile time In computer science, compile time (or compile-time) describes the time window during which a language's statements are converted into binary instructions for the processor to execute. The term is used as an adjective to describe concepts relat ...

is when source code is translated into

machine code In computer programming, machine code is computer code consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). For conventional binary computers, machine code is the binaryOn nonb ...

by a

compiler In computing, a compiler is a computer program that Translator (computing), translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primaril ...

. Part of this involves language checking, such as ensuring proper use of the

type system In computer programming, a type system is a logical system comprising a set of rules that assigns a property called a ''type'' (for example, integer, floating point, string) to every '' term'' (a word, phrase, or other set of symbols). Usu ...

. The result of a successful compilation is an

executable In computer science, executable code, an executable file, or an executable program, sometimes simply referred to as an executable or binary, causes a computer "to perform indicated tasks according to encoded instruction (computer science), in ...

. Link time connects all of the necessary machine code components of a program, including externals. It is very common for programs to use functions implemented by external

libraries A library is a collection of Book, books, and possibly other Document, materials and Media (communication), media, that is accessible for use by its members and members of allied institutions. Libraries provide physical (hard copies) or electron ...

, all of which must be properly linked together. There are two types of linking. Static linking is when the connection is made by the compiler, which is always prior to execution.

Dynamic linking In computing, a dynamic linker is the part of an operating system that loads and links the shared libraries needed by an executable when it is executed (at " run time"), by copying the content of libraries from persistent storage to RAM, fill ...

, however, is performed by the

operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...

(OS) just before, or even during, execution. Distribution time is the process of transferring a copy of a program to a user. The distribution format is typically an executable, but may also be source code, especially for a program written in an

interpreted language In computer science, an interpreter is a computer program that directly executes instructions written in a programming or scripting language, without requiring them previously to have been compiled into a machine language program. An inter ...

. The means of distribution can be physical media such as a

USB flash drive A flash drive (also thumb drive, memory stick, and pen drive/pendrive) is a data storage device that includes flash memory with an integrated USB interface. A typical USB drive is removable, rewritable, and smaller than an optical disc, and u ...

or a remote download via the

Internet The Internet (or internet) is the Global network, global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a internetworking, network of networks ...

. Installation time gets the distributed program ready for execution on the user's computer, which often includes storing the executable for future loading by the OS. Load time is when the OS takes the program's executable from storage, such as a

hard drive A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating hard disk drive platter, pla ...

, and places it into active

memory Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembe ...

, in order to begin execution. Run time is the execution phase, when the

central processing unit A central processing unit (CPU), also called a central processor, main processor, or just processor, is the primary Processor (computing), processor in a given computer. Its electronic circuitry executes Instruction (computing), instructions ...

executes the program's machine code instructions. Programs may run indefinitely. If execution terminates it will either be normal, expected behavior or an abnormality such as a crash. Programming language implementation