Before we start, if you haven't finished reading The Basics and Multiple Options articles you may want to read that first.
Now that you know the details around having the ads code in a central location (for multiple agencies) and using the same in your website or blog, in this article I will have details around showing the ads from different agencies in random fashion.
If you dont have programming expertise, read The Basics article first before proceeding.
If you own a blog or website then it is very important to make sure that we maintain better user experience while displaying the ads. Just think about it. How annoying it feels when the reader sees the ads that are out of place (like mobile size ads on desktops, out of size etc.). I don't have to give an example site as there are tons of sites that you may have already encountered that way.
Before we start, if you haven't finished reading The Basics article you may want to read that first.
If you have a blog or self managed website, it is almost given that you are signed up with one of the ad programs (Google's AdSense, Commission Junction, Affiliate programs with Amazon or similar ones). It is easy to manage the code given by these agencies initially but when you have more blog posts it kind of becomes messy and time consuming. For example if you want to change an ad or agency or have your own responsive ad, it is a pain to update all the previous posts when the site is grown to a decent size.