The purpose of KOMA-scripts

I want to ask a question about KOMA-scripts.

I’m a beginner in LaTeX and I’m trying to understand the term KOMA-Scripts that appears repeatedly throughout the LaTeX wiki.

As far as I can make out, the current version of LaTeX is LaTeX2e, and KOMA-Scripts apparently introduce update the keywords to the standard document classes e.g. article, book, letter etc, while introducing new packages e.g. scrlayer-scrpage. In the tutorial shown here, I see that there is no change to the standard document class, nor any mention of KOMA-Scripts being imported, yet it exists in the environment and simply one can import scrlayer-scrpage` with incredible ease.

However, I’ve failed to find any resource on the internet that provides a comprehensive analysis of how KOMA-Scripts work and its purpose for a beginner like myself, especially when learning how to personalise headers and footers in LaTeX.

What are KOMA-Scripts, in layman’s terms, and how are they implemented in LaTeX?