Spam is a growing problem that most blogs deal with. Fortunately you can prevent comment spam by using these methods.
Reviewing comments- With most blogging platforms you can set for comments to be moderated before they are published. This will stop all comment spam from reaching your blog.
Filtering comments- This is where you can set for the comment to be reviewed or not published if it has a certain word or element in it that you don’t want in the comments.
To be most effective you should combine these two methods for your blog comments.