what is bootstrap? i looked up in internet but i didnt understand well

Answer 1

Build fast, responsive sites with Bootstrap
Quickly design and customize responsive mobile-first sites with Bootstrap, the world’s most popular front-end open source toolkit, featuring Sass variables and mixins, responsive grid system, extensive prebuilt components, and powerful JavaScript plugins.

https://getbootstrap.com

https://getbootstrap.com/docs/5.1/getting-started/introduction