Software development is the computer programming, documenting, testing, and bug
fixing involved in creating and maintaining applications and frameworks involved
in a software release life cycle and resulting in a software product. The term refers
to a process of writing and maintaining the source code, but in a broader sense
of the term it includes all that is involved between the conception of the desired
software through to the final manifestation of the software, ideally in a planned
and structured process. Therefore, software development may include research, new
development, prototyping, modification, reuse, re-engineering, maintenance, or any
other activities that result in software products
Software can be developed for a variety of purposes, the three most common being
to meet specific needs of a specific client/business (the case with custom software),
to meet a perceived need of some set of potential users (the case with commercial
and open source software), or for personal use (e.g. a scientist may write software
to automate a mundane task). Embedded software development, that is, the development
of embedded software such as used for controlling consumer products, requires the
development process to be integrated with the development of the controlled physical
product.
Software Development Activities
Planning
Planning is an objective of each and every activity, where we want to discover things
that belong to the project. An important task in creating a software program is
extracting the requirements or requirements analysis. Customers typically have an
abstract idea of what they want as an end result, but do not know what software
should do. Skilled and experienced software engineers recognize incomplete, ambiguous,
or even contradictory requirements at this point. Frequently demonstrating live
code may help reduce the risk that the requirements are incorrect.
Once the general requirements are gathered from the client, an analysis of the scope
of the development should be determined and clearly stated. This is often called
a scope document.
Designing
Once the requirements are established, the design of the software can be established
in a software design document. This involves a preliminary, or high-level design
of the main modules with an overall picture (such as a block diagram) of how the
parts fit together. The language, operating system, and hardware components should
all be known at this time. Then a detailed or low-level design is created, perhaps
with prototyping as proof-of-concept or to firm up requirements.
Implementation, testing and documenting
Implementation is the part of the process where software engineers actually program
the code for the project. Software testing is an integral and important phase of
the software development process. This part of the process ensures that defects
are recognized as soon as possible. Documenting the internal design of software
for the purpose of future maintenance and enhancement is done throughout development.
This may also include the writing of an API, be it external or internal. The software
engineering process chosen by the developing team will determine how much internal
documentation (if any) is necessary. Plan-driven models (e.g., Waterfall) generally
produce more documentation than Agile models.
Deployment and maintenance
Deployment starts directly after the code is appropriately tested, approved for
release, and sold or otherwise distributed into a production environment. This may
involve installation, customization (such as by setting parameters to the customer's
values), testing, and possibly an extended period of evaluation.[citation needed]
Software training and support is important, as software is only effective if it
is used correctly.[citation needed] Maintaining and enhancing software to cope with
newly discovered faults or requirements can take substantial time and effort, as
missed requirements may force redesign of the software