The standard editor commands are available to create and manipulate a selection.
Select menu commands:
Select All - selects the entire image (Ctrl+A on Windows, ⌘+A on Mac).
Deselect - cancels the selection (Ctrl+D on Windows, ⌘+D on Mac).
Reselect - restores the previous selection (Ctrl+Shift+D on Windows, ⌘+⇧+D on Mac).
Invert - unselects currently selected parts and selects currently unselected parts (Ctrl+Shift+I on Windows, ⌘+⇧+I on Mac).
Transform Selection - lets transform the selection edges without affecting the image content.
Edit menu commands:
Cut - cuts the selected area of the current layer to the clipboard (Ctrl+X on Windows, ⌘+X on Mac).
Copy - copies the selected area of the current layer to the clipboard (Ctrl+C on Windows, ⌘+C on Mac).
Copy Merged - copies the selected area of merged layers and places it on the clipboard (Ctrl+Shift+C on Windows, ⌘+⇧+C on Mac).
Paste - inserts the contents of the clipboard into a new layer (Ctrl+V on Windows, ⌘+V on Mac).
Erase - removes the selected area of the current layer (Delete).
Layers -> New menu commands:
Layer via Copy - creates a new layer by copying the selected area of the current layer (Ctrl+J on Windows, ⌘+J on Mac).
Layer via Cut - creates a new layer by cutting the selected area of the current layer (Ctrl+Shift+J on Windows, ⌘+⇧+J on Mac).