Using Static Resources

Static resources allow you to upload content that you can reference in a Visualforce page, including archives (such as .zip and .jar files), images, style sheets, JavaScript, and other files.
Using a static resource is preferable to uploading a file to the Documents tab because:
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In addition, using static resources to refer to JavaScript or cascading style sheets (CSS) is preferable to including the markup inline. Managing this kind of content using static resources allows you to have a consistent look and feel for all your pages and a shared set of JavaScript functionality.

A single static resource can be up to 5 MB in size, and an organization can have up to 250 MB of static resources, total.