Correct terminology to properly search
<p>I have some programming experience (mid-2nd year of 4 year program, and some personal experience) writing  programs in Java, C, Javascript, PHP, etc... And now I want to learn more on my own about writing executables that pass information between eachother and remain "idle", but active in the meantime. This has not been covered yet, but I'll need it for a personal project. </p>

<p>Can anyone tell me what that concept is called, and perhaps where to begin, so I can start learning about it?</p>
