A snippet could be one of two things, depending on what you’re talking about.
The first, also known as a code snippet, is a small section of code from a program, usually just a few lines. Good code snippets can be reused, which encourages better code organization, quicker development, and better-performing programs. It also makes programs much easier to improve or upgrade in the future.
The second is related to search engine optimization (SEO) and refers to a single search result on a search engine results page (SERPs). A snippet contains the page’s title, uniform resource locator (URL), and a little info about the page. A good way of controlling a page’s snippet, and, consequently, what a user sees in the SERPs, is by adding a meta description.