Anonymous functions, in a simple way, are functions that can be activated directly without declaring his name, as his own name says "anonymous".
This technic works in C# projects, .NET Framework, .NET Core or WPF and can be used to reduce code, on this POST I attached a sample of using anonymous X common (regular) way.
The final result is a reduced code and fast startup.

The common way

Below is a regular code for fired Click events. To run this Form there is extra code in FormCommon.Designer.cs.
FrmCommon.cs
  1. using System;
  2. using System.Windows.Forms;
  3. namespace AnonymousEventsForClick
  4. {
  5. public partial class FrmCommon : Form
  6. {
  7. public FrmCommon()
  8. {
  9. InitializeComponent();
  10. }
  11. private void menu1ToolStripMenuItem_Click(object sender, EventArgs e)
  12. {
  13. // Your code
  14. // CODE xyz
  15. var n = 0;
  16. APIProject.Print(++n);
  17. }
  18. private void checkBox1_CheckedChanged(object sender, EventArgs e)
  19. {
  20. APIProject.CheckStatus();
  21. }
  22. private void button1_Click(object sender, EventArgs e)
  23. {
  24. // Sample to access the object
  25. if (!(sender is Button)) return;
  26. APIProject.OpenDocument();
  27. }
  28. }
  29. }
FrmCommon.Desingner.cs
Extra code
...
this.menu1ToolStripMenuItem.Click += new System.EventHandler(this.menu1ToolStripMenuItem_Click);
...
this.button1.Click += new System.EventHandler(this.button1_Click);
...
this.checkBox1.CheckedChanged += new System.EventHandler(this.checkBox1_CheckedChanged);
...

The Anonymous way

Below is the same code with anonymous functions to fire events, with fewer functions, lines, and usings. There is no extra code in FrmAnonymous.Designer.cs.
  1. using System.Windows.Forms;
  2. namespace AnonymousEventsForClick
  3. {
  4. public partial class FrmAnonymous : Form
  5. {
  6. public FrmAnonymous()
  7. {
  8. InitializeComponent();
  9. menu1ToolStripMenuItem.Click += (s, e) =>
  10. {
  11. // You can add your code in the body
  12. // CODE xyz
  13. var n = 0;
  14. APIProject.Print(++n);
  15. };
  16. checkBox1.CheckedChanged += (s, e) => { APIProject.CheckStatus(); };
  17. button1.Click += (s, e) =>
  18. {
  19. // Sample to access the object
  20. if (!(s is Button)) return;
  21. APIProject.OpenDocument();
  22. };
  23. }
  24. }
  25. }

CONCLUSION

Using this technic you can reduce code and organize it in a single place.
Anonymous functions can be used to any kind of Events, this sample shows only for the Click event.
Happy coding.