Default output filename

[generalentropy]

Hi,

I don't understand clearly how filenames work by default.
For example, let's say that I have different files in my src folder:

index.html
favicon.png
finder.js
logo.png
icon.svg
and some sass files.

The output in the dist folder is

index.html
index.8b2f57bf.css
index.e37f48ea.js
icon.21bad73c.svg
logo.726d37a8.png
favicon.21bad73c.png

Why are some files named with the original filename as a prefix while others are not?

Why my CSS and js files are named with "index" ?