The following XAML example specifies the background color of a button as red. This example illustrates a case where the simple string value for a XAML attribute is type-converted by the XAML loader into a WPF type (a Color, by way of a SolidColorBrush) in the generated code.

<Button Background="Red" Content="Button!"/>

XAML supports a variety of syntax forms for setting properties. Which syntax to use for a particular property will depend on the value type that a property uses, as well as other factors such as the presence of a type converter. For more information on XAML syntax for property setting, see XAML Overview and XAML Syntax Terminology.

As an example of non-attribute syntax, the following XAML example shows another button background. This time rather than setting a simple solid color, the background is set to an image, with an element representing that image and the source of that image specified as an attribute of the nested element. This is an example of property element syntax.

<Button Content="Button!">
  <Button.Background>
    <ImageBrush ImageSource="wavy.jpg"/>
  </Button.Background>
</Button>

Setting dependency property values in code is typically just a call to the set implementation exposed by the CLR "wrapper". 

Button myButton = new Button();
myButton.Width = 200.0;

Getting a property value is also essentially a call to the get "wrapper" implementation:

double whatWidth;
whatWidth = myButton.Width;

You can also call the property system APIs GetValue and SetValue directly. This is not typically necessary if you are using existing properties (the wrappers are more convenient, and provide better exposure of the property for developer tools), but calling the APIs directly is appropriate for certain scenarios.

Properties can be also set in XAML and then accessed later in code, through code-behind. For details, see Code-Behind and XAML.

A dependency property value can be set by referencing a resource. Resources are typically specified as child elements of a page root element, or of the application (these locations enable the most convenient access to the resource). The following example shows how to define a SolidColorBrush resource.

<DockPanel.Resources>
  <SolidColorBrush x:Key="MyBrush" Color="Gold"/>
</DockPanel.Resources>

Once the resource is defined, you can reference the resource and use it to provide a property value:

<Button Background="{DynamicResource MyBrush}" Content="I am gold" />

This particular resource is referenced as a DynamicResource Markup Extension (in XAML, you can use either a static or dynamic resource reference). To use a dynamic resource reference, you must be setting to a dependency property, so it is specifically the dynamic resource reference usage that is enabled by the WPF property system. For more information, see Resources Overview.

Note:
Resources are treated as a local value, which means that if you set another local value, you will eliminate the resource reference. For details, see Dependency Property Value Precedence.

A dependency property can reference a value through data binding. Data binding works through a specific markup extension syntax in XAML, or the Binding object in code. With data binding, the final property value determination is deferred until run time, at which time the value is obtained from a data source.

The following example sets the Content property for a Button, using a binding in XAML. The binding uses an inherited data context and an XmlDataProvider data source (not shown). The binding itself specifies the desired source property by XPath within the data source.

<Button Content="{Binding XPath=Team/@TeamName}"/>

Note:
Bindings are treated as a local value, which means that if you set another local value, you will eliminate the binding. For details, see Dependency Property Value Precedence.

Dependency properties, or the DependencyObject class, do not natively support INotifyPropertyChanged for purposes of producing notifications of changes in DependencyObject source property value for data binding operations. For more information on how to create properties for use in data binding that can report changes to a data binding target, see Data Binding Overview.

Styles and templates are two of the chief motivating scenarios for using dependency properties. Styles are particularly useful for setting properties that define application user interface (UI). Styles are typically defined as resources in XAML. Styles interact with the property system because they typically contain "setters" for particular properties, as well as "triggers" that change a property value based on the real-time value for another property.

The following example creates a very simple style (which would be defined inside a Resources dictionary, not shown), then applies that style directly to the Style property for a Button. The setter within the style sets the Background property for a styled Button to green.

<Style x:Key="GreenButtonStyle">
  <Setter Property="Control.Background" Value="Green"/>
</Style>

<Button Style="{StaticResource GreenButtonStyle}">I am green!</Button>

For more information, see Styling and Templating.

Dependency properties can be animated. When an animation is applied and is running, the animated value operates at a higher precedence than any value (such as a local value) that the property otherwise has.

The following example animates the Background on a Button property (technically, the Background is animated by using property element syntax to specify a blank SolidColorBrush as the Background, then the Color property of that SolidColorBrush is the property that is directly animated).

<Button>I am animated
  <Button.Background>
    <SolidColorBrush x:Name="AnimBrush"/>
  </Button.Background>
  <Button.Triggers>
    <EventTrigger RoutedEvent="Button.Loaded">
      <BeginStoryboard>
        <Storyboard>
          <ColorAnimation
            Storyboard.TargetName="AnimBrush" 
            Storyboard.TargetProperty="(SolidColorBrush.Color)"
            From="Red" To="Green" Duration="0:0:5" 
            AutoReverse="True" RepeatBehavior="Forever" />
        </Storyboard>
      </BeginStoryboard>
    </EventTrigger>
  </Button.Triggers>
</Button>

For more information on animating properties, see Animation Overview and Storyboards Overview.

You can change certain behaviors of a dependency property by overriding the metadata for that property when you derive from the class that originally registers the dependency property. Overriding metadata relies on the DependencyProperty identifier. Overriding metadata does not require re-implementing the property. The metadata change is handled natively by the property system; each class potentially holds individual metadata for all properties that are inherited from base classes, on a per-type basis.

The following example overrides metadata for a dependency property DefaultStyleKey. Overriding this particular dependency property metadata is part of an implementation pattern that creates controls that can use default styles from themes.

public class SpinnerControl : ItemsControl
{
    static SpinnerControl()
    {
        DefaultStyleKeyProperty.OverrideMetadata(
            typeof(SpinnerControl), 
            new FrameworkPropertyMetadata(typeof(SpinnerControl))
        );
    }
}

For more information about overriding or obtaining property metadata, see Dependency Property Metadata.

An element can inherit the value of a dependency property from its parent in the tree.

Note:

Property value inheritance behavior is not globally enabled for all dependency properties, because the calculation time for inheritance does have some performance impact. Property value inheritance is typically only enabled for properties where a particular scenario suggests that property value inheritance is appropriate. You can determine whether a dependency property inherits by looking at the Dependency Property Information section for that dependency property in the SDK reference.

The following example shows a binding, and sets the DataContext property that specifies the source of the binding, which was not shown in the earlier binding example. The value of the DataContext property inherits by property value inheritance to all child objects in the logical tree. Any subsequent bindings in child objects do not need to specify the source, they can use the inherited value from DataContext in the parent StackPanel object. (Alternatively, a child object could instead choose to directly specify its own DataContext or a Source in the Binding, and to deliberately not use the inherited value for data context of its bindings.)

<StackPanel Canvas.Top="50" DataContext="{Binding Source={StaticResource XmlTeamsSource}}">
  <Button Content="{Binding XPath=Team/@TeamName}"/>
</StackPanel>

For more information, see Property Value Inheritance.

A custom control with properties that are implemented as dependency properties will receive appropriate Windows Presentation Foundation (WPF) Designer for Visual Studio support. One example is the ability to edit direct and attached dependency properties with the Properties window. For more information, see Control Authoring Overview.

Typically, you would not want styles to always apply and to obscure even a locally set value of an individual element (otherwise, it would be very difficult to use either styles or elements in general). Therefore, the values that come from styles operate at a lower precedent than a locally set value. For a more thorough listing of dependency properties and where a dependency property effective value might come from, see Dependency Property Value Precedence.

Note:
There are a number of properties defined on WPF elements that are not dependency properties. By and large, properties were implemented as dependency properties only when there were needs to support at least one of the scenarios enabled by the property system: data binding, styling, animation, default value support, inheritance, attached properties, or invalidation.