MySQL replication - how to read from slaves? manually?

MySQL Manual - Replication - "Scale-out solutions - spreading the load among multiple slaves to improve performance. In this environment, all writes and updates must take place on the master server. Reads, however, may take place on one or more slaves. "

I see how to setup replication which looks relatively simple, but I haven't seen how an application should communicate to slaves.

I assume the application would have to determine which slave to read from? The application will also have to know which server is doing writes? Or is it possible to have the application send all queries to the Master and have reads proxied to slaves?