A Microsoft file hosting and synchronization service.
You can check your storage usage by signing in to the OneDrive website or visiting your Microsoft Account dashboard.
On the web, go to OneDrive, sign in, and look at the bottom-left corner of the page to see your used space. In Windows, click the blue OneDrive cloud icon in your taskbar, open Settings, and look at your account details. On mobile, open the OneDrive app, tap your profile icon, and check Storage Usage.
If you cancel your paid OneDrive or Microsoft 365 subscription, your storage allowance drops back to the free 5 GB limit. If you are using more than 5 GB, your files become read-only after the applicable grace period, although you can still download them to your computer. If you remain over the 5 GB limit for more than six months, Microsoft may delete files, so you should download or move important files before that happens.
For most people, Microsoft 365 provides better value than purchasing standalone OneDrive storage because Microsoft 365 plans include OneDrive storage along with additional benefits. Microsoft 365 Personal and Family provide 1 TB of OneDrive storage per user, along with desktop versions of Word, Excel, PowerPoint, and other Microsoft 365 applications.
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hth
Marcin