Ever since Google started to offer users a GMail e-mail account, which includes storage space of a 1000 megabytes, you have had plenty of storage space but not a lot to fill it up with.
With GMail Drive you can easily copy files to your GMail account and retrieve them again. When you create a new file using GMail Drive, it generates an e-mail and posts it to your account.
The e-mail appears in your normal Inbox folder, and the file is attached as an e-mail attachment. GMail Drive periodically checks your mail account (using the GMail search function) to see if new files have arrived and to rebuild the directory structures.
But basically GMail Drive acts as any other hard-drive installed on your computer.
You can copy files to and from the GMail Drive folder simply by using drag'n'drop like you're used to with the normal Explorer folders.
Because the GMail files will clutter up your Inbox folder, you may wish to create a filter in GMail to automatically move the files (prefixed with the GMAILFS letters) to your archived mail folder.
Please note that GMail Drive is still an experimental tool. There's still a number of limitations of the file-system (such as total filename size must be less than 40 characters), and it doesn't make full use of the secure internet protocols available.
Link :
Gmail Drive