Document properties, also known as metadata, are details about a file that describe or identify it. They include details such as title, author name, subject, and keywords that identify the document's topic or contents. If you include the document properties for your files, you can easily organize and identify them later. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.