There are a number of best practices when it comes to optimizing your Database's speed and performance.
Indexes are a powerful tool used to speed up querying data. You can think of an index similar to a table of contents of "index" in the back of a book. When you want to quickly lookup something, you refer to the index and jump to the page. Xano automatically indexes your data in the most performant way it knows how, but if you want to provide a specific pointer to data that's important to you in the table, you would define a new Index.