If you have a blog or website and want to make extra money, you can become an Amazon Associate—linking to products on Amazon. Every time one of your followers clicks on one of those links and buys a product from Amazon.co.uk, you earn referral fees.

“Amazon makes it easy for you to earn money whenever your readers actually buy the products you write about. This is known as an "affiliate programme," and it's designed to let you recommend products you like to your audience—if they buy the product, you'll earn a commission on that purchase.”
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The Amazon Associates programme was one of the first progammes of its kind in the world. The Amazon Associates programme doesn't just empower bloggers to make money by advertising millions of products from Amazon on their websites—you can also earn revenue if you're a website owner, web developer or Amazon seller.

"Once you get people to visit Amazon (pretty much for any reason), a percentage of them will naturally end up buying something. The cool thing is that whether they buy the thing you linked to or not—you'll earn a commission."— Darren Rowse, ProBlogger