[runfalk]

A task queue or message queue is generally used to delegate jobs to worker processes.

Imagine you are GitHub and a user comments on an issue that has 1000 people participating. As soon as the user makes a comment you want to send an email to every user that there are new comments.

The straight forward way is to do that in the web application when the comment is posted, but that takes a lot of time and leaves the commenter staring at a loading screen until everyone is notified. (There are other reasons as well)

With a message/task queue you would create 1000 messages (each saying "send e-mail about this issue to this user"). Then you have worker processes that in a loop look at one message at a time and sends an e-email. When the message is sent the worker marks (acks) that message as handled and it is removed from the message/task queue.