An environment is a segment of text that is managed differently than the rest of the document. For example, you create a report with font size 12, but you need to change your font size for a few sentences. The commands \begin{environment}, \huge and \end{environment} will let you temporarily alter the text inside the environment commands to be size huge.

Changes are only effective from \begin{environment} to \end{environment}. There are no limits as how many changes you can make inside an environment.

There are many features you can add to your document that will make it more readable and user-friendly. You can add features such as specific fonts, bold, italics, underline etc. to your document, and these commands will end with either an \end command, or at the end of your environment.