Vim yanking range of lines

I'm a C# developer who has just recently decided to expand my knowledge of the tools available to me. The first tool I've decided to learn is Vi/Vim. Everything has been going well so far, but there are a couple of questions I can't seem to find the answer to:

1. Lets say I wanted to yank a range of lines. I know there are many ways of doing so, but I would like to do it by line number. I figured it would be similar to how the substitute commands work, something like 81,91y. Is there a way to do this?

2. I'm a little confused about the g command in normal mode. It seems to do a myriad of things and I can't really determine what the g command does at its core. I'm confused on whether or not it's a motion command or a kind of "catch all" for other commands ran through normal mode. Can someone please explain this or point me to a reference that gives a good explanation of the g command?

Yank lines 81-91

:81,91y<enter>

If your fingers don't like to find the : and , keys, this would work as well (go to line 81, yank 11 lines)

81gg11yy 

My only use of g is 5gg. To go to the 5th line. 22gg: 22nd line. As jimbo said, it's really only a modifier for some other commands.

For completeness, (http://vim.wikia.com/wiki/Power_of_g) explains a lot of how g works in command mode.

You can also copy the current lines to your present cursor location using 't'.

:81,91t.<enter>

This will paste the lines 81-91 under the line the cursor is on.

I learned this from http://vimcasts.org which is an excellent resource on VIM.

I also like to use vim's relative line number option which means I can just enter:

:-10,-7ya a

to yank the text into named buffer a.

N.B. Specifying A will append what you're yanking to the current contents of buffer a.

Don't forget you can also copy blocks of text and move blocks of text around as well with the similar commands:

:-10,-7co .

means copy the four lines of text 10 lines above to below the current line, and

:-10,-7mo .

means move the four lines of text 10 lines above to below the current line.

The G command goes to a certain line number, if it's accompanied by a count value. 81G puts you on line 81.

The y command can be combined with a movement, like G. So to yank everything until line 91 you can use y91G.

Together you get:

81Gy91G

Go to line 81, then yank while going to line 91.

g doesn't do anything by itself. It's one of a couple meta-commands that holds a bunch of sorta-unrelated commands.

z is yet another command like that.