Explaining caching, in a nutshell, is probably harder than actually solving the problems caching can cause when delivering ads. So please bear with me.
Table of Contents
Imagine the stream of data when a visitor is coming to your website to be like this (very simplified):
user – browser – address lookup – server – programing language (PHP) – database – PHP – server – browser – user
Especially between the programing language and the database, the communication is like crazy. They exchange information about the navigation, post content, images, user rights, etc. to build even the most uncomplicated websites. All this communication happens for each visitor on each page view, even if it looks the same to everyone.
On larger websites, there are a lot of these identical page views. With a lot of visitors, the performance is put to the test.
Imagine buying a puzzle with the picture of the Statue of Liberty because you saw the box with the great-looking image on it in the show window. Once you put all the pieces together and hang it on your office wall, your colleagues also want to have it. So they all go to the shop, buy the puzzle, put it together and hang it on their walls.
To secure excellent performance and high-speed websites, people who are a lot smarter than I invented caching. Caching simply stores bigger junks of information, so not every small piece needs to be requested and put together repeatedly.
In the case of a website, this can mean storing some parts or the whole website code. This code is later prepared for your request and gets sent to your browser. They already know how it will look like for you because it seems the same to everyone.
After so many of your colleagues spend their valuable office hours putting together the same puzzle, the smart boss shot a photo of the puzzle on the wall and sent a digital copy to all colleagues. Everyone who wants it now just has to open their email and print the image. This saves a lot of time and energy.
As you can see in the example above, the result is still the same (a beautiful picture on the wall). But the way towards it is a lot shorter. The work that is done once does not have to be repeated because the result is stored somewhere in between the user and the raw data.
Caching in WordPress
In the case of WordPress, there are basically two ways to enable caching. One is by using a Caching Plugin, the other is server caching offered by your hosting company.
Some widely used caching plugins are:
- WP Rocket
- W3 Total Cache
- WP Super Cache
If one of these or similar plug-ins is installed in your WordPress environment, it is possible that caching is enabled on your site.
The server cache is provided by your hosting company. Especially WordPress dedicated services often have cache enabled. Since caching is an important feature, you will probably spot this easily in the product or service description. If not, just ask them about it.
The downsides of ad caching
Caching is as great for pages that are identical for every visitor. But it causes problems on pages with even the smallest differences. In the case of ads, this can be a simple ad rotation.
Imagine you want to do a split test of two different banners in the same position and, therefore, create an ad group with two ads in Advanced Ads. The information about the ads is stored in the database. If the page is cached after the first visitors saw it, every following visitor will see the exact same content, including the same ad.
This can still be a split test, especially if the caching time is rather low (a few hours), and the ads are displayed on different pages. But you should still be aware of this.
Advanced Ads and the different add-ons do their best to provide solutions for cached websites since most of my own sites use very advanced caching methods themselves. However, there are always differences between ad delivery on cached sites and on those that put together the puzzle for each page request.