Unwanted advertising

I would welcome any help with an issue I have with unsolicited advertising on my iMac. I get adverts popping up everywhere, even in my mail words are highlighted such that if you click on it an advert pops up. I use OS X with the Mavericks update. The company whose name pop up is "Gophoto.it V9. 0"
Can anyone guide me in the right direction to remove this rubbish from my system please ?

Here you go.

Brilliant. Thank you very much.

That has been annoying me for several weeks now. I am indebted to you

Thank you, thank you, thank you.

Dennis

Also consider using Adblock and Ghostery.

Harry, thanks for your reply but what is Adblock and Ghostery ?

Just tried looking up both sites and discovered what they are all about. Wonderful tools and have just installed both.

How many more people out there are unaware how to control the intrusions on our pc's.

Thanks guys.

Dennis

Although sites such as this one depend on advertising to keep the lights on (and thus you should whitelist this site from Adblock), I have to wonder if there is any such thing as WANTED advertising.

I hear what you say Chas and yes the sites do rely on advertising for revenue. But the advertisers must realise that most of us hate inadvertent advertising. Personally on the rare occasion I have tele sale people on the phone then I am abusive to them, same with door to door callers. If I want information then I will seek out the info by all the means available.

But I have no desire to be bombarded with ads for products I do not want.

Therefore very grateful to Van & Harry and your input of course.