How to block behavioural adverts that follow you around while you browse

You've probably noticed recently that you keep seeing the same ad repeated time and time again on lots of different websites you've been going to. Over the last year or so it's been irritating me more and more - while I understand websites need ad revenues to survive, I also think that for me this is one step too far - particularly when the ad isn't relevant to me and yet I get presented with it every single day of my life! So as of today I'm blocking all behavioural advertising and as far as possible, anything that tracks me while I use the web. You might want to do the same. Here are some handy ways to get rid of these irritating behavioural ads that seem to follow you around the internet and just won't go away.