Grid Based Design

This is an approach that web designers use for easily laying things out. It divides the page into a grid, which enables you to visualise and plan out where you should put what. It also enables you to take total advantage of a person's eye-line.

Responsive Webpages

These allow you to look at the website on any device. Whether it's a laptop, tablet, or phone. As phones and tablet viewing becomes more popular, these are almost essential. Responsive webpages are designed to be aesthetically pleasing and easy/comfortable to use anywhere, any time.

Semantic Structure

Just as in the English language, HTML language has different ways to be interpreted. Changing the placement of a word in a sentence can completely alter the meaning. In HTML, it's equally important to get the meaning of your sentence right - to ensure everything is placed correctly and will be interpreted properly.