Most blogs and web pages include some kind of advertisement. It is one way to capitalize the time spent in the web edition.
One of the most common advertisements type is Google AdWords, based on the browser history and visitor's behaviour, in order to (in theory) offer targeted ads, matching his/her preferences and likes. It is a way to optimize advertisement spaces, reducing their negative impact.
This way, in this blog you can see ads between posts, or in the middle of longer ones. If your computer, tablet or cellphone is connected to a Google account (Google+, GMail...), you will see, most likely, ads related to your previous searches or purchases. If you log out of these accounts and erase all navigation data (history, cache, cookies...), advertisements will change.
Curious, isn't it? On one side, this strategy can help your work, or your Internet searches. But, on the other side, this shows the control that companies like Google have over your personal data - something that can be really disturbing... What do you think?
By the way, I know there are some links that are interesting to you. From time to time, please open some of these... You do not need to purchase anything, but this will show Google that my blog gets some visits - and they will treat me well :)