There are two kinds of Library in InDesign: 'CC' Libraries and 'regular' Libraries. This video covers the use of 'regular' Libraries. 'CC' Libraries are covered in a separate video later on. I use Libraries to hold all the specific colour swatches and paragraph styles that a particular client uses. then, all I need to do is open the library, drag the item onto the page, and delete it and it's already been added to swatches and/or paragraph styles windows.