Spam blogs are blogs that are made to spread unwanted messages and advertising, such as ads for products or services. This is done by making webpages that all look the same but link to different websites, or by leaving spam comments like ads on other people's blogs. They are called spam because they are trying to spread the same message to a lot of people in a short amount of time, like someone spreading junk mail in your mailbox. These blogs are usually annoying and can slow down your access to other websites.