With a Mac you can also hold down "Command" and press "C", then to paste hold down "Command" and press "V".
To copy and paste a link you click on the web address box at the top of the page and it highlights it in blue. Then you copy and paste as usual.
To copy some text you click at the beginning of it and drag down as far as you want to copy, then release the mouse. It will highlight all you "drug" over. Takes a little practice sometimes to get the highlighting to end where you want it to.
One other thing I learned ........ if you're typing a reply, and you suddenly lose the page, click on the "back" arrow ( looks like this < ) at the upper left of the screen. It will often take you right back to the reply page you were typing. It's saved me from retyping stuff many times.
SRH