HTML5 (No space between "HTML" and "5")is a markup language used for structuring and presenting content on the World Wide Web. It is the fifth and current version of the HTML standard.
It was published in 28 October 2014, W3C also published an HTML 5.1 Candidate Recommendation on 21 June 2016. The World Wide Web Consortium (W3C) to improve the language with support for the latest multimedia, while keeping it both easily readable by humans and consistently understood by computers and devices such as web browsers. HTML5 is intended to subsume not only HTML 4, but also XHTML 1 and Document Object Model (DOM) Level 2 HTML.
The CSS was started to develop around 1998. And till 2009, it was under development. The first working draft of CSS3 came in 19-01-2001. but it was initially declared early in the June 1999. The main difference between css2 and css3 is Media Queries, Namespaces, Selectors Level 3, Color.
Bootstrap includes a responsive, mobile first fluid grid system that appropriately scales up to 12 columns as the device or viewport size increases. It includes predefined classes for easy layout options, as well as powerful mixins for generating more semantic layouts.