The Summary of your Article
The summary of your article is displayed in the categories listing to give the visitors a brief idea about the information they will find.

It will also be used in the Meta Tag description, which is used by the search engines to evaluate the content of a web page.
Here is an example:

You can use up to 150 characters to describe your article.
Create a summary which gives a brief idea about your article and encourages the visitor to read further.