ISO 12207 is an ISO standard for software lifecycle processes. It aims to be 'the' standard that defines all the tasks required for developing and maintaining software.
The ISO 12207 standard establishes a process of lifecycle for software, including processes and activities applied during the acquisition and configuration of the services of the system. Each Process has a set of outcomes associated with it. There are 23 Processes, 95 Activities, 325 Tasks and 224 Outcomes (the new "ISO/IEC 12207:2008 Systems and software engineering -- Software life cycle processes" defines 43 system and software processes).
The standard has the main objective of supplying a common structure so that the buyers, suppliers, developers, maintainers, operators, managers and technicians involved with the software development use a common language. This common language is established in the form of well defined processes. The structure of the standard was intended to be conceived in a flexible, modular way so as to be adaptable to the necessities of whoever uses it. The standard is based on two basic principles: modularity and responsibility. Modularity means processes with minimum coupling and maximum cohesion. Responsibility means to establish a responsibility for each process, facilitating the application of the standard in projects where many people can be legally involved.
The set of processes, activities and tasks can be adapted according to the software project. These processes are classified in three types: basic, for support and organizational. The support and organizational processes must exist independently of the organization and the project being executed. The basic processes are instantiated according to the situation.