What is continuous integration? [closed]

This is by far the best explanation I have read so far.

At its simplest, it is simply a mechanism that rebuilds your project whenever a check in is made into some revision control system (CVS etc). This can be extended though to include running tests, all the way through to generating a CD image, mounting it within VMs, installing the product and running full tests on it.

It has the simple advantage of highlighting when code changes break the system as early as possible. Not only does it detect breaks in the code, it highlights who caused the break. This psychological effect is very effective in encouraging good testing prior to check in!

It is the practice of ensuring that all aspects of your software development process are lined up to permit the daily creation of a working version of your product. It is best known as part of Extreme Programming.

This involves things as far afield as build automation, automated testing, daily check-ins, using a source code repository, etc. But the ultimate goal is to help the entire project run according to core Agile Principles so that you deliver early and often. This, in turn, helps you leverage feedback from your users, etc.