# Overview

![](https://developers.google.com/static/wallet/tickets/closed-loop/images/closed-loop-tall.png)

Google Wallet for Transit has two different solutions that are termed *closed loop*:

1. The emulation of closed loop cards
2. The ability to save and convey a token that represents a backend account

In both cases, these transit cards can only be used within the transit agency's network.

## Emulation of closed loop cards

Google Wallet for Transit enables the emulation of closed loop cards for public transit
agencies with popular protocols such as MIFARE DESFire and MIFARE Plus, CMD2 (ITSO), and others.
This solution acts the same way as a physical card, where the phone is the source of truth and the
phone simply emulates the behavior of a typical closed loop plastic card.

This lets Public Transit Operators (PTOs) issue virtual cards with the same protocols used by
their existing fare validators. This is most suitable for agencies with complex fare rules on the
gate terminals who don't plan to enable an account-based system.

For more details, see
[Prerequisites](https://developers.google.com/wallet/tickets/closed-loop/get-started/prerequisites).

## Account-based cards with tokens on the phone

Google Wallet for Transit enables new account-based solutions, where the transit agency
maintains a backend account for each user. In this case, the phone only holds an account
identifier, and the source of truth is on the transit agency server. This is similar to a typical
bank account model.

Google Wallet supports EMVCo-based transit tokens, described here as a Private Label Card
(PLC), and acts as the account identifier. This solution uses the same technology as open loop
payments for the conveyance to the terminal, but the PLC is usable only within the network of the
transit agency.

Public Transit Operators (PTOs) who already support open loop payments can use the same
EMVCo-based technology on their fare validators.

For more details, see
[Prerequisites](https://developers.google.com/wallet/tickets/closed-loop/get-started/prerequisites?protocol=private-label).

## Solution

Transit agencies that integrate with one of the preceding solutions can let users purchase and
store a virtual transit card on their mobile device. These cards can have a prepaid balance,
passes, or both. The cards show important information, such as available balance, and ticket
details like expiry, validity of pass, recent transactions, or travel history.

Users can also top-up their balance or purchase additional tickets directly through
Google Wallet or through a transit agency's own app. There is minimal visual UI difference
between a closed loop card and an account-based card.