The Full-Text Engine manages full-text indexes. The engine splits your text columns into individual terms and builds an inverted index, mapping each term back to the rows in which it appears. Unlike a standard B-tree index, the structure lives outside the normal index internals and is maintained asynchronously via a background process called a crawl. Effectively, each word in your text string ends up indexed, rather than the string as a whole. This makes certain types of searches much more efficient (you need to use search terms like CONTAINS() to utilize full text indexes).
If you have to search strings like this then full-text indexes can be very effective. String searching isn’t great in SQL Server, but this is definitely a tool in your belt if you have a requirement that makes it useful.
Because of some changes to the way full-text indexing works in SQL Server 2025, there is a post-upgrade maintenance task you’ll have to perform.