LESS is a CSS pre-processor, which means that it composes styles in a dynamic fashion. By allowing you to create a library of variables, functions and other effects, LESS makes CSS writing more efficient by making it easier and faster.
HTML5 is the fifth revision of the well-known and loved markup language. There are many new features and abilities that HTML5 has to offer and this post will get you familiarized with them. I will not go into in-depth detail about every aspect of HTML5, but I will get you familiarized with its key aspects; after all, this is only an introduction to HTML5.