HTTP Caching in Ruby on Rails Applications

A general way to describe caching is storing some data so that we can quickly retrieve it later. Sometimes, this means storing computed data so that it does not need to be re-computed, but it can also refer to storing data locally to avoid having to fetch it again. Your computer does this constantly, as your operating system tries to keep frequently accessed data in RAM so that it doesn't have to be fetched again from a hard drive or SSD.Similarly, your browser tries to re-use resources it has already downloaded. You've probably seen this yourself when visiting a new website for the first time. The initial load takes longer because your browser has to pull down everything it needs, including all the images, javascript, and stylesheets. A fun fact is that when you freshly download the CNN homepage, your browser fetches more data than the original Doom game circa 1993. For the curious, at the time of writing this blog post, CNN downloads just over 3MB on my machine, compressed from ~15MB, and that's with an ad blocker enabled, while the original Doom installer was ~2.2MB.