The rein is the subtle connection between the rider's hand and the horse.
And this connection is not a one-way street: the rein signals can pass back and forth.
When you start working with reins, here's a tip: use reins with a clip on both ends.
Because with these clips you can attach the reins to the rings of the cavesson and change them around easily.
As you become more advanced, you can use a combination of cavesson and bit during work in hand and riding.
This is where you start to work with two reins.
Now if you are working with two reins it is, especially in the beginning, advisable to use different reins.
For example a brown one for the cavesson and a black one for the bit.
Or a wider one for the cavesson and a smaller one for the bit.
Because you see, by using different reins you will not get confused, and you can easily make the distinction between cavesson rein and bit rein.