All HTML information begins with an open angle bracket, <, and ends with a close angle bracket, >, e.g. <HTML>.
These pieces of information are called tags.
The tags tell the browser how to format and layout the information in a document.
HTML tags are either stand-alone units or paired.
A paired HTML tag has a beginning tag, open tag, and an ending tag, close tag. Syntax is <tag-name> for an open tag and </tag-name> for close tag. It's good practice to remember the close tags.
See an example (The skeleton of an html document.)