An abstract C# class that allows subscribers of derived classes to be notified of property value changes.

ObservableObject.cs

using System.ComponentModel;
using System.Runtime.CompilerServices;

/// <summary>
/// Represents an object that notifies subscribers of property value changes.
/// Implements the <see cref="INotifyPropertyChanged"/> interface.
/// </summary>
public abstract class ObservableObject : INotifyPropertyChanged
{
    /// <summary>
    /// Occurs when a property value changes.
    /// </summary>
    public event PropertyChangedEventHandler? PropertyChanged;

    /// <summary>
    /// Raises the <see cref="PropertyChanged"/> event for the specified property.
    /// </summary>
    /// <param name="propertyName">
    /// The name of the property that changed. 
    /// This value is automatically supplied by the compiler when called from the property setter.
    /// </param>
    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null!)
    {
        if (PropertyChanged != null)
        {
            var e = new PropertyChangedEventArgs(propertyName);
            PropertyChanged(this, e);
        }
    }
}