If you have a blog, or a message board, or a guest book, you probably had to install something against spam. For obvious reasons, blogs and other types of community sites with user participation are a great attraction to these scam bags.
The reason spammers choose to overflow other sites with their links is that the existence of these links, even if nobody actually clicks them, increases their artificial search engine ranking.
Before I began this blog I installed a street photography forum on my site which was a nice place for street photographers to talk about related issues and review each other photos.
But very quickly the spam robots discovered this forum and began posting their links in the older discussion threads. Back then the anti-spam practice was to ban ip addresses and certain key words but other than that there was nothing much to do.

Minolta SRT 101 . Kodak T400 CN BW film . Malibu 2009

Now days it is much easier to prevent spam in comments.
There are many ways to fight spam like installing automated spam detectors, rejecting links in posts, members participation only, using the “nofollow” tag (which in my opinion is not at all effective), and of course the most irritating anti-spam method; the CAPTCHA. This is when you need to validate your message by entering a combination of letters and numbers before you can post your comment.
Needless to say that this method tends to get on everybody’s nerves when so often the letters are impossible to read that it takes a few tries before the form is finally submitted.
When I installed my blog I made sure to add an anti-spam plugin called Akismet, which works just fine. It always finds the spam and leaves it in a folder on the server for me to go over and make sure it is all spam alright. Until recently, I didn’t mind checking this spam folder every once in a while and deleting the spam, but suddenly there are more and more spam comments and going over the spam folder became more time consuming.
So I decided to simply install another plugin which requires the posters to review their posts before they submit them. It is a very simple fix but quite smart. It lets people review their comments and at the same time it prevents the automated spam comments from being posted.
So far, in the last couple of weeks there were no comments in the spam folder. It is empty.
Seems like problem solved.