Accounts provide a way to guardedly and securely store and retrieve sensitive data like passwords, security tokens etc. Accounts should be created first using "Add/Update Account" task and then they can be accessed using "Load Account" task. If an action makes use of an account then the user will be prompted to grant access to that account. 

To access properties of an account - use common dot operator followed by a property name e.g. account.password. Only textual properties are currently allowed for account. Due to security reasons, it is not possible to list all the properties of an account, making impossible to utilize Variable Keyboard. So you must remember property names to access them.

Some accounts may allow authorization in order to provide access to third-party cloud services. For such accounts, appropriate authorization actions (sign-in and sign-out) must be provided. Usually, a sign-in action should utilize the AOuth protocol to prompt the user to sign-in, handle sign-in result, store user credentials and access token in the account. Optional sign-out action should remove user credentials and access token from the account and optionally notify cloud service about sign-out.

All the accounts are listed in the Alloy's "Settings | Accounts | Custom Accounts" sections. Any account may be deleted using common swipe gesture. For accounts that allow authentication, it is possible to check their status, see signed-in users and perform sign in/out actions.

For complete sample, check "Action Directory/Samples" for "Dropbox Browser", "Dropbox Sign-in" and "Dropbox Sign-out" actions.  

See also:
"Load Account" Task
"Add/Update Account" Task