The auto login feature for wallets is the ability to enable PKI-based access to services without requiring human intervention to supply the necessary passwords. Enabling auto login creates an obfuscated copy of the wallet, which is then used automatically until the auto login feature is disabled for that wallet.
Auto login wallets are protected by file system permissions. When auto login is enabled for a wallet, only the operating system user who created it can manage it, through the Oracle Wallet Manager.
You must enable auto login if you want single sign-on access to multiple Oracle databases: such access is normally disabled, by default. Sometimes the obfuscated auto login wallets are called "SSO wallets" because they support single sign-on capability.