Data Binding is a technique that is used to synchronize the source of the data with the user interface. When the data binding is done and the data or our business model changes, then it shows the changes automatically to the UI elements and vice versa.

Binding Mode is used to provide the direction in which property value changes are made.

OneWay
In One way binding, the changes are made from its source to the target.

TwoWay
In Two-way binding, the changes are made in both the directions and Two-way binding makes sure that the source and the target are always synchronized.

OneWayToSource
Changes are made from the target to the source and are mainly used for read-only bind-able properties. In Xamarin.Forms Mode property is default set to OneWay.