For starters, what is a blog? In general terms, it is a sort of interactive, regularly updated online journal. A blog owner is called a blogger, the activity of keeping a blog is called blogging, and the blogging community and everything related to blogging is collectively known as the blogosphere.
How are blogs created? There are several options. The cost-free way is to start a blog at one of the countless free blog services, such as the Google service called blogger. Another option is to use one of the free blog scripts and install it at a paid or free hosting service. Such free blog scripts are also numerous, the most popular of them being wordpress. It is also possible to sign up for a paid hosting service with an already installed wordpress blog, but this service is somewhat costlier.
Now let's assume that we already have a blog. The next question is: Where do we get content? Choose the subject for your blog. It may be your professional occupation or hobby. In any case, you must have solid knowledge of the subject. For instance, if you are a proctologist, you may write about hemorrhoids, their treatment, prevention and suchlike as long as these are not scientific articles, but materials written in layman's language. To give you a more practical example, if your hobby is dogs, write about them and people will enjoy it. There is another way to get content. The web has many services offering free articles. All you have to do is select the most interesting ones and publish them. In this way you can quickly fill your blog with content.
Moving on to the question of promoting your blog, it is worth noting that blogs are better indexed by search engines than ordinary web sites due to the specifics of the algorithm used in blogs. For instance, a new article in a well-promoted blog may appear on the search engine results page already on the following day. Of course, this requires registration in special catalogs devoted to blogs, which is what you will do next. Another way is to publish articles with a link to your blog. There are also services meant for just this purpose.
But most importantly, a search engine needs external links to your blog from other web sites. These should be good links generating heavy traffic. What does it mean? It means that ideally the link should be on the web site's main page. What's more, this page should have a PR rating of at least 4 (PR or Google Page Rank reflects the significance of any particular web page). Five or six such links will do more than hundreds of other ordinary links. How can you get such links? There are also various options. For instance, you can find a resource thematically related to your blog and offer its owners to reciprocate links. Finally, you can buy such links. The higher the web site's PR rating, the more such links will cost you.
Now let's move on to the question of how you can earn money from your own blog. The scheme is quite simple: traffic is converted into money. Your income increases proportionately with the traffic volume. One way to earn from a blog is to place ads, which is done most often through google adwords. Another way is to participate in partnership programs associated with the subject of your blog. So if your blog is devoted to dogs, you should advertise flea control products and other dog-related merchandise. A third way is to sell your own merchandise or services. Of course, you can combine several ways of generating income in a single blog. Last but not least, remember that strength is in numbers, which is why it's a good idea to maintain several resources at the same time.