Keystroke: ⌘+C
Copy is used to place a duplicate of the current highlighted text into the clipboard, so that you can insert it elsewhere. Use Paste to insert the copy to a new position in the document, or into another application. The text remains highlighted even after you have given a command, (e.g. Ctrl + c to copy), until such time as you use a mouse click - or a navigation key such as one of the arrow keys - to remove the highlighting.
Note: When pasting into another application, there are some limitations. Such things as DBT Codes will not be pasted as seen. Likewise, if you copy and paste from a document in Braille view, you will not necessarily see braille dots on the screen when you paste.
See also: Edit: Cut