Vi search and replace

After 20 years of working on UNIX I am just now finding the need to learn more than the basics of VI. (Yes I have been a emacs person for many many years.) Here is how to do a global search and replace in vi.

 1,$s/oldstring/newstring/g  

The 1 means the first line of the file (obvious) and $ means the last line of the file (less obvious).