Many developers spend time writing code designed to extract a very specific number of words or characters from a piece of text. This text sample, often drawn from a blog post or comment, is usually displayed with a link that leads the user to read more. You can see an example on this site in the extracts of articles added to favorites in user profile pages.
Using a thoroughly organized content management schema that divides every article into a lede, nut graph, and body units of text minimizes the need for string manipulation. However, such units are not always available or applicable.