OneDrive is a free online file storage service that allows users to store and access files from any device. Files can be added to OneDrive from a computer by dragging them into the OneDrive folder, from a phone or tablet using the OneDrive app, or from any device using the OneDrive website. Once files are in OneDrive, they can be easily shared or collaborated on with others. OneDrive also integrates with Windows and Office programs to allow files to be accessed and edited from any device.