Tagging has been implemented for posts, so I'll be retroactively adding tags to previous posts.
Tags, not hashtags, because the # symbol is only used to indicate its attribute (just as @ is designated for addresses), which can be as easily done with hyperlinks.
Simple enough; added another column to the SQL table and store all the tags into that column, and open and split when accessed. Apparently it's more efficient to create a new table, but the repeated access and write would be impractical for my editing page. It may be required later as the table grows, but for the foreseeable future, this should work fine.
Tags are searchable (otherwise known as functional), and can list all articles that are also tagged with the same tag, and can also list all tags currently in use.
Changing the formatting should be fairly easy, but implementing the tagging system early on allows for minimal retroactive tagging later.