Encrypting folders and files is a way to protect them from unwanted access. Encrypting File System (EFS) is a feature of Windows that allows you to store information on your hard disk in an encrypted format. Encryption is the strongest protection that Windows provides to help you keep your information secure.
Right-click the folder or file you want to encrypt, and then click Properties.
Click the General tab, and then click Advanced.
Select the Encrypt contents to secure data check box, and then click OK.
The first time you encrypt a folder or file, you should back up your encryption certificate. If your certificate and key are lost or damaged and you do not have a backup, you won't be able to use the files that you have encrypted.
Right-click the folder or file you want to decrypt, and then click Properties.
Clear the Encrypt contents to secure data check box, and then click OK.