1. What is Bootstrap? Front-End Framework Mobile First
Front-End Framework
Mobile First
Solves cross-browser issues (normalize.css)
Open-source, most popular such framework
But what is Bootstrap? It is a collection of folders and files for you to use in the design of your website: CSS, Javascript, Fonts (glyphicons) You can download them (.zip) or link to them at a content delivery network (cdn). Website:
What is Bootstrap?

11. Mobile First
Solves cross-browser issues (normalize.css)
Open-source, most popular such framework
But what is Bootstrap? It is a collection of folders and files for you to use in the design of your website: CSS, Javascript, Fonts (glyphicons) You can download them (.zip) or link to them at a content delivery network (cdn).
Customizing Bootstrap There are 2 Approaches- Edit bootstrap.css or use cutom.css

12. Customizing Bootstrap – 2 Approaches
1-) Edit bootsrap.css (Ctrl-f search for the component of interest) .jumbotron { padding-top: 30px; padding-bottom: 30px; margin-bottom: 30px; color: inherit; background-color: #eee; } 2-) Create Custom.css (Copy and paste code from bootstrap.css) .jumbotron { padding-top: 30px; padding-bottom: 30px; margin-bottom: 30px; color: inherit; background-color: #eee; } * If the link to custom.css comes after the link to bootstrap.css, the custom rule will be followed.