WordPress is probably the best publishing platform available for normal users on the internet; however, it does not come with every option enabled out-of-the-box. If you have been using wordpress since the start, you must have noticed that the current version contains many features which were only possible with plugins in earlier versions.
But there are still some features that are missing from the current version of wordpress such as Related Posts. Related posts feature displays a list of links to posts that are similar to the current page. It makes your blog more readable. When the reader finds something similar to the page he is reading, he is more likely to click the related post link.
You can use plugins such as Yet Another Related Posts, but many believe that using too many plugins slows down your wordpress blog. So if you know a little about editing html and php files, you can easily add the code available on techatlast to the Single.php file of your theme.
I have tried the above code, and it works flawlessly on any theme. But always make sure to take a backup of your theme files before you venture out to edit. Sometimes small mistakes can bring your WordPress blog to a screeching halt.