Rails async queries by example - Honeybadger Developer Blog

First, let's make sure we understand what the words "synchronous" and "asynchronous" mean. When something is executed synchronously, it means that the work is connected, or dependent in some way, often requiring one task to be completed before the next can start. Synchronous things happen one after another, like people moving through a line. This is of course in contrast to "asynchronous" which means that the tasks are independent of one another and thus can be completed at the same time. Asynchronous things can (but don't have to) happen at the same time. For a more tangible, real-world example, consider the following.