How shareable links work in OneDrive and SharePoint in Microsoft 365
When users share files and folders in Microsoft 365, a shareable link is created which has permissions to the item. There are three primary link types:
Anyone links give access to the item to anyone who has the link. People using an Anyone link don't have to authenticate, and their access can't be audited.
An anyone link is a transferrable, revocable secret key. It's transferrable because it can be forwarded to others. It's revocable because by deleting the link, you can revoke the access of everyone who got it through the link. It's secret because it can't be guessed or derived. The only way to get access is to get the link, and the only way to get the link is for somebody to give it to you. Anyone links can't be used with files in a Teams shared channel site.
People in your organization links work for only people inside your Microsoft 365 organization. (They don't work for guests in the directory, only members).
Like an anyone link, a people in my organization link is a transferrable, revocable secret key. Unlike an anyone link, these links only work for people inside your Microsoft 365 organization. When somebody opens a people in my organization link, they need to be authenticated as a member in your directory. If they're not currently signed-in, they're prompted to sign in.
Specific people links only work for the people that users specify when they share the item.
A specific people link is a nontransferable, revocable secret key. Unlike anyone and people in my organization links, a specific people link don't work if they're opened by anybody other than the person specified by the sender.
Specific people links can be used to share with users in the organization and people outside the organization. In both cases, the recipient needs to authenticate as the user specified in the link. For files in a Teams shared channel site, specific people links can only be sent to others in the channel.
It's important to educate your users in how these sharing links work and which they should use to best maintain the security of your data. Send your users links to Share OneDrive files and folders and Share SharePoint files or folders, and include information about your organization's policies for sharing information.