It is true that many people earn a full time income from blogging. Everyone uses different ways to make money from their blog.
Here are different ways other people make money from blogging or for full course you can check how to start a blog
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1. Show Ads To Your Readers
This is easiest and mostly used by beginners. It works only if you have a lot of traffic. Income is quite low but very consistent. Just sign up at google adsense or buysellads to get started.
2. Sell other people products for commissions( Affiliate Marketing)
Many bloggers recommend products to their audience. If someone buys it through them then they get a commission for the sale.
3. Sell your own eBook
This one is quite easy. Write an eBook. Put it in amazon kindle and promote on your blog.
4. Sell your courses. Teach online.
There are many people looking to learn things and they are willing to pay for it. You can create a course on udemy or provide private coaching.
5. Sell your product.
It can be anything that people want. A software or a physical product.
6. Sell your services (Freelance).
Many bloggers I know make money from this method.