Annoying ads

i know its hard to see based on this picture but there are two ads that are on the page. One of them is for new phones, and the other is for new cars and car accesories. Over my many years of surfing the web i have noticed that if i or anybody else searches a topic a lot of times it will start popping up in little ads all over the place. Its really annoying because it will be on like every website i go on. Ill try to go on twitter or a stores website and little ads about whatever ive been searching pop up asking if i want to visit the website where i can get it ON SALE or with FREE SHIPPING.

Do companies that want to advertise pay extra money to pester us or do the search engines automatically do this?I dont see what type of technique or appeal that they can be using other than annoyance and hindrance. And if it the search engines do they have permission to monitor what we search and then try and make us buy it? i feel like the media is trying to get too connected to our everyday lifes and by these ads popping up all the time that proves it.