When an IDE says it's indexing what does that mean? What is actually going on "under the hood"? Is it safe for me to build my project during it indexing or should I wait until it's finished indexing?
I'm assuming indexing is a common thing for IDEs but I've never had an explanation of indexing. I simply see the word indexing and think "I know that word, must be doing something." and I just take it for granted and expect it to happen.
What is indexing?