This article explains why people who are active on the Internet should maintain a weblog.
The Article Edit
You probably know what a "Blog", or "Weblog" - an online journal of entries - is. This article aims to tell you why you should blog and a bit on how. Blogs have become a bit passé and old-technology in the eyes of many "hipsters" and "youngsters" (who now tend to prefer such Internet mediums as Facebook or Twitter), but they are still very popular and news sites will much more more often link to a blog post than to a Twitter feed or something obscure on Facebook, which isn't easily linkable.
The first reason you need to blog is to practise and improve your writing skills. Writing is a positive "addiction" - the more you write, the more you have more to write about, and the more and better you write and so forth. People will criticise your writing on many aspects of it, and you'll be able to improve it. Since language and conceptual thought is primarily a tool of thinking and only secondarily a tool of communication, becoming a better writer will make you a better thinker - i.e: a brighter and more intelligent person.
The second reason you may wish to blog is to gain some esteem and recognition. You'll probably won't become the next big "IT" blogger such as "Joel on Software" or "Wil Wheaton dot Net (in Exile)" but you may still gain some respect and recognition and be able to have something to show for some prospective employers (and those who will look down upon the fact that you maintain a blog usually won't be good employers, anyhow).
The third reason is surprisingly to learn what to do to write things that people like to read. The median blog in English, as far as quality is concerned, is probably very low, and probably contains posts that explain what people with boring lives did the day before, which are of little interest to anyone except their family and very close friends. If you want to have a blog like that, it's OK, but it's a better idea to write a blog that people will read.
You shouldn't fall into the usual angst, that says that people had bad tastes in what is popular. If something is popular, and people are not forced to enjoy it, you can assume it has some minimal value to it that can appeal to a large amount of people. I'm not advocating conformism here - a lot of non-mainstream culture is popular in its own right, and has made its creator millionaires, while most people may still considered it as bad. You can never please all the people all the time.
Similarly, the best way to have a popular blog is to write about a specialised topic. Anything. You can start a blog about cooking, even cooking of something very specific. You can start a blog with interesting posts about cats. You can blog about a Hawaiian word of the day. You can blog about something considered relatively passé such as the Perl programming language or the Oracle Database or even COBOL or the Pascal programming language. Some people will be interested enough to read it. Like Eric Sink said on a blog post on a different topic, you should aim for a small niche.
I have some reasons to mostly blog in English instead of in Hebrew, which is my mother language and the day-to-day language where I live. However, by blogging in your native language, you may be able to achieve a smaller niche of people who will be able to relate better. On the other hand, it is harder to reach the global audience and attention of global news sites and the global intelligentsia, who still know enough English. Perhaps you'd like to have more than one blog in each language.
It's probably not a good idea to regularly mix entries of more than one language in the weblog - start one blog in each language you'd like to blog in.