In July I turned on word verification for this blog, forcing people to type in a random word before adding comments.
The purpose of this is to prevent spammers from using programs to add automated comments to the blog, which has become a real nuisance.
I'm now turning word verification off again for a trial period, because Blogger has implemented a new spam-filtering system. I'll see how it goes.
27th of October: I've turned word verification back on, because the blog is receiving about 20 spam messages a day, and the spam filtering system doesn't reduce the nuisance much. I still get all of them arriving in my e-mail inbox, and still have to delete all of them. Much better if they don't get onto the blog in the first place. I'm sorry it means a little extra trouble for anyone wanting to post messages on the blog; blame the spammers.