Copy and paste works the same as in other operating systems. First select the text, so that it appears highlighted, usually in blue. Then press Ctrl–C. Now move the keyboard focus to the right position. Finally, to insert the text, press Ctrl–V.
To copy or paste in the terminal, additionally press Shift together with the above key combinations.
An alternative way of using copy and paste is described in the following. First select the text. To paste the text, middle-click over the position where you want the text to be pasted. As soon as you make another selection, the text from the original selection will be replaced in the clipboard.
When copying information between programs, you must keep the source program open and paste the text before closing it. When a program closes, any content from that application that is on the clipboard is lost.