| A [*protocol*][protocol-doc-link] describes a set of methods that can be | |
| invoked by sending messages over a channel. It describes the interface over | |
| which FIDL data may be exchanged between a client and a server. | |
| <<../examples/calculator/_callout.md>> | |
| <<../examples/calculator/_baseline_tutorial.md>> | |
| [protocol-doc-link]: /docs/reference/fidl/language/language.md#protocols |