I believe that every administrator of a dynamic website has at least once encountered issues when updating content due to cache problems.
But what exactly is cache in this specific case? I want to clarify this because there are different types of cache at various levels, both server-side and client-side.
The cache is a temporary memory where specific website contents are stored temporarily to limit the requests and responses between the server and the browser and vice versa. This helps save resources and speeds up content loading.
Let's assume a visitor is browsing a website from their computer.
So, what happens with the cache? The visitor's browser downloads and displays the various pages and their contents while simultaneously storing in the cache images, CSS files, JS files, and, in general, all the contents that originate from the website's server. At this point, the browser's cache holds all the contents that have been downloaded and viewed. It's as if a snapshot of all previously viewed pages has been taken.
When a visitor decides to go back and view a page they had opened before, the browser will show them the snapshot taken earlier, saving time and resources for everyone involved: the user's browser CPU load, the website server's CPU load, the visitor's data usage, and the server's data usage.
Usually, you don't notice these "snapshots" because website content doesn't change that frequently.
However, cache and its mechanisms become noticeable when you manage a website. For example, you know you've changed an image in the admin panel, but due to cache, the old image still appears. To view the new image, you must manually clear the browser's cache to trick the software into thinking it's the first time you've visited that page.
