# What e-mobility is

> How electric vehicle charging actually works, and why it is more than a card swipe.

E-mobility is the mix of hardware, software and commercial agreements that lets an electric vehicle charge and pay for energy, anywhere, across networks that are owned and run by different companies. A driver should be able to pull up to more or less any public charging station, start a session, and be billed correctly, without caring who owns the charging station or which app they signed up with.

## Why it is harder than a card payment

A card payment is one shopper, one terminal, one bank rail. A charging transaction is not.

- **Two sides that rarely belong to the same company.** The charging station is operated by one business, and the driver's account or card is issued by another. They have to agree, in real time, that this driver may charge here and who will pay.
- **Closed-loop authorisation.** Most public charging is authorised with an RFID card or an app token over a private network, not with a bank card at the point of use. The money is reconciled afterwards between the operators.
- **Real-time state.** Whether a charging station is free, how much power it can deliver, and what it costs are all published live across the network so drivers can find and trust a charge.
- **Metered, variable cost.** The price depends on energy delivered, time, location and tariff, and is only final once the session ends.
- **Settlement between businesses.** After the session, the operators settle with each other, and the driver's provider bills the driver. One physical charge can touch four or five systems in under a second.

## The shape of the ecosystem

Two roles sit at the centre. A **Charge Point Operator (CPO)** owns and runs the charging hardware. An **eMobility Service Provider (eMSP)** gives drivers a way to access charging (a card, an app, an account) and bills them. **Roaming** is the set of agreements and interfaces that let an eMSP's drivers use a CPO's charging stations even when the two are different companies. **Hubs** interconnect many CPOs and eMSPs so each one integrates once instead of many times.

Two open protocols carry almost all of this. **OCPP** connects a charging station to the software that manages it. **OCPI** connects operators to each other for roaming. The rest of this primer walks through the players, the anatomy of a single charging session, and those two protocols, and ends with a glossary of the vocabulary you will meet everywhere else in these docs.