What are the styles in bootstrap?

Question

css

https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/cs...
https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/cs...
Please explain why to enable Bootstrap you need to include 2 .css files?
That is, why did you decide to split the connection into 2 files, and not put all the styles in 1 file?? What is the difference between these 2 files?

Answer 1

you need to include 2 .css files

there is no such need
1st is the styles of the framework, and
the 2nd theme to it, if simple, then the color scheme