A library in SharePoint is a special list built specifically for managing files and the metadata around them. Libraries are similar to lists in that:

• Just like list items in SharePoint lists, libraries contain individual files that you can work with.
• Just as columns in lists define the information that gets stored as part of each list item, columns in libraries define the metadata that you can associate with each file. Once the columns for a library are defined, you can tag individual files with appropriate metadata.
• Similar to how you manage information in lists individually or together as a group of items, you can manage metadata in libraries individually or as part of groups of items.
• Just like list items, you can also individually manage permissions for these files.

From these perspectives (and in a lot of other ways...