Select the text or item you want to copy
Press Command (⌘) + C to copy
Place the cursor where you want to paste
Press Command (⌘) + V to paste
To cut instead of copy, select the text or item and press Command (⌘) + X
To paste without formatting, use Command (⌘) + Option (⌥) + Shift (⇧) + V
To copy using the menu bar, select the text or item, then choose Edit > Copy
To paste using the menu bar, place the cursor, then choose Edit > Paste
To copy/paste with a trackpad, click and drag to select, then use two-finger tap for the context menu and choose Copy/Paste