There are so many WordPress “related posts” plugins – it’s hard to figure out which one may be best for you. Some work better than others, some have different algorithms, and I’ve had one or two myself that conflicted with other installed plugins, so I had to remove it and move to a better alternative.
The related post plugin I’ve used the longest, and that seems to have the least amount of overhead, never breaks, and has nearly no conflicts at all is Aizatto’s Related Posts.
The Yet Another Related Posts plugin is also highly rated, and has been downloaded thousands of times.
Sometimes you don’t want just related posts, you might want to also look at the WordPress Popular Posts Plugin.
Custom Post Relationships Plugin
This plugin is nice because you can actually choose which related posts are displayed. If you need this kind of functionality it works great, but it doesn’t display related posts automatically (you have to manually add the code to your theme), and you have to manually choose the posts.
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