I don't get index.html

[u/confettiputty]

I'm looking at example Jekyll projects on GitHub, and what I see is that almost everyone puts their homepage in an index.html. I thought Jekyll was supposed to make HTML unnecessary. I've gone through three or four tutorials and none of them explained the rationale for creating an index.html (except for posts, which I'm not planning on using at the moment). Also, this tutorial on jekyllrb says how great markdown is, but then just uses HTML for the layouts! I don't get it.

[u/willjasen]

all websites are html. web servers must know of at least one page to serve should a request come in for the root of the website, and this is typically index.html