What Characters Are Allowed in WordPress Taxonomy Terms?
WordPress Tags, Categories and other taxonomy terms are in important part of WordPress. They are the normal way to organize your WordPress content.
However, terms are different from posts, media files, menus and other WordPress features. They are stored separately in the WordPress database. They have their own restrictions on what you can and can not do with them. This includes the characters you use inside terms.
You can use apostrophes, hashtags and other characters in terms
WordPress will accept many different characters as terms. If you add a character is not in the roman alphabet from A-Z or 0-9 then WordPress will still create the term successfully. What happens is that WordPress will use the ID number of term for the permalink. So in the image below the term using a hashtag is term number 53, so that becomes the URL. The slug for this will be /category/53/. This guide has more on term slugs.
In fact, you also use characters from other languages. In the image below, I've successfully added terms i Japanese and Arabic. In these examples, the full original characters are used for the permalink.
You can use commas in terms
It is possible to use commas in terms, but they are treated slightly differently from other characters.
So it is allowed to have Tags and Categories such as “Los Angeles, California”. The best way to create these terms is from the “Category” area or “Tags” are in your WordPress admin menu. In this image below, the Category will be created correctly. The slug for this will be /category/los-angeles-california.
However, you can add Tags with commas while you are writing posts. This is because the “Tags” box will immediately separate the phrase into two terms as soon as you add the comma.
Summary of allowed taxonomy characters
So WordPress will allow you to add almost any character as a taxonomy term. However, I will add a note of caution. Because of the way these characters are encoded, unusual characters may not always play nicely with third party plugins and themes. If you do add some of these unusual characters, keep an eye out in case they are not being displayed correctly.