1. Bootstrap
According to Wikepedia, Bootstrap is a free collection of tools for creating websites and web applications. It contains HTML and CSS-based design templates for typography, forms, buttons, navigation and other interface components, as well as optional JavaScript extensions.
According to Twitter developer Mark Otto:
"A super small group of developers and I got together to design and build a new internal tool and saw an opportunity to do something more. Through that process, we saw ourselves build something much more substantial than another internal tool. Months later, we ended up with an early version of Bootstrap as a way to document and share common design patterns and assets within the company."
Features
Bootstrap is compatible with the latest versions of all major browsers. It gracefully degrades when used on older browsers such as Internet Explorer 8.
Since version 2.0 it also supports responsive web design. This means the layout of web pages adjusts dynamically, taking into account the characteristics of the device used (desktop, tablet, mobile phone).
Starting with version 3.0, Bootstrap adopted a mobile first design philosophy, emphasizing responsive design by default.
Bootstrap is open source and available on GitHub. Developers are encouraged to participate in the project and make their own contributions to the platform.
Structure and Function
Bootstrap is modular and consists essentially of a series of LESS stylesheets that implement the various components of the toolkit. A stylesheet called bootstrap.less includes the components stylesheets. Developers can adapt the Bootstrap file itself, selecting the components they wish to use in their project.
Adjustments are possible to a limited extent through a central configuration stylesheet. More profound changes are possible by the LESS declarations.
The use of LESS stylesheet language allows the use of variables, functions and operators, nested selectors, as well