Categories vs Tags is one of the biggest decisions around how you setup a good taxonomy using WordPress. Utilising both categories and tags can make your site easier to navigate which will help both people and search engines. It has taken me a while to get my head around this so thought I would run through my thoughts in the hope that it might help shape your decision making.
Categories in my opinion are best used for the main structure of your site and can be thought about a bit like a menu. Each post should only be present in one category. Categories can also have sub categories, this can be handy to split your content down into more specific areas when you have enough posts. A good example of this would be sport, for example for on a news based site you are quite like to have sport as a top level category, then under that individual sports such as football and cricket.
Tags in my opinion are best used to cut across categories and a post should have many tags but only one category. Tags have the advantage of being able to be combined to bring back more specific data when required. I think a good example of this would be a tag for “David Beckham”, as he is both a footballer and a celebrity he could appear under either a sport or celebrity category and if you wanted to get more specific you could search for both “David Beckham” + “Victoria Beckham” if you are interested in their goings on or “David Beckham” + “LA Galaxy” if you wanted to know about his latest sport endeavours.
Ensuring that your taxonomy is clean and consistent can really help both people and robots navigate your site. Starting out in the right way with the right structure will lead to better results for everyone as changing later can be quite detrimental to any search juice that you have built up especially if you have the category name in your URL.
Music to Write this Code to
My mate @josephshell going deep on the house tip for his night Milkface