More common is affiliate marketing - you earn a fee via an agency from a company if someone buys its products after clicking through from your site.
If the reader buys the knife you earn commission on that sale.
However, the first step with blogging is to be honest with yourself.
He started his newsletter blog in 2003, sent to friends and families, and in 2012 sold the resulting website to for a cool £87m.
Ms Wallin, who has a background in marketing, posts on her blog once a week, combining it with part-time paid work and childcare.
Less obscure names may well be sold out or come at a higher price.
If your blog takes off and you get a good level of traffic, you're likely to be contacted by companies offering affiliate marketing.
Ms Gilmour said percentages varied from around 5pc to 15pc.
She started her site two and-a-half years ago with the help of her husband, a website designer. "As with all freelance work, the earnings are not predictable.
I think it is obvious in a blog if all it's about is making money." Another way to make money can be through sponsored posts: for example, a cakedecorating company might sponsor a food blogger's cake recipes.
Wendy Gilmour, who blogs on fashion and style on her site around three times a week and has about 10,000 hits a month, does sponsored contact with selected retailers.
Have you got anything interesting to say in a blog that no one else is saying?