What the intention of the "components" variable?

For every IDE generated UserControl C# file, there are some identical code :

/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;

/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}

However, I can't find any other place that uses components variables. Is it will always be null? What's the intention of this variable?

Thanks!

[792 byte] By [LeiJiang] at [2007-12-16]