There is no doubt that backlinking is a vital section of internet marketing now a days. You cannot do the optimization of your site for search engine without this backlinking section. Backlinking brings lots of traffic to your site. And of course increase the page rank of your site.
Now the question is, where and how can I do the backlinking? Generally most of sites now a days have a comment section. This comment section is provided for the feedback of the writing of that site. You can do a meaningful comment with a link of your site there. Some comments sites have a pattern to give your name, email address and site name like the following one-
In the name section you can give your name or the keyword or anchor text of your backlinks. Give your mail address in the mail adress section and give the site address of your site in the address section. Finally make a meaningful comment in the comment section. Be careful about that because most of the sites moderate all of the comments made. If your comment is not meaningful it might be deleted by the moderator.
What should be done if the site does not have the name and link section! Just check that whether the comment section supports some tags or not. If the comment section section supports HTML tags you can do the backlinks like the following format.
This HTML tags is also known as bb code, you can just use the same system to use the bb code. And if the section supports something other just use the way it need to be used.
There is terms named link exchanging. You can exchange your site links to the other site owners. This is of course another types of link building.