This is so it can first be compiled to ensure that all required dependencies are present, and possibly tested to show no bugs have been introduced.
The daily build is also often publicly available allowing access to the latest features for feedback.
In this context, a build is the result of compiling and linking all the files that make up a program.
The use of such disciplined procedures as daily builds is particularly necessary in large organizations where many programmers are working on a single piece of software.
The critical piece of this process is to include new and revised tests as the project progresses.