If you click the left mouse button on the icon in the top left corner of PuTTY's terminal window, or click the right mouse button on the title bar, you will see the standard Windows system menu containing items like Minimise, Move, Size and Close.
PuTTY's system menu contains extra program features in addition to the Windows standard options. These extra menu commands are described below.
(These options are also available in a context menu brought up by holding Ctrl and clicking with the right mouse button anywhere in the PuTTY window.)