If you have a website and you have some text that you need to change, the Find and replace action saves you time to do the whole process.
For example, lets see this website, a common thing that many people do is leaving the Copyright unchanged, so you may go to a website
that is updated but still, the copyright says 2005 when we are in 2007.
So what we need is to replace all the copyrights in our website, difficult? No way, look:

Lets open one page of the many pages our website has:

Lets go to the copyright text, as you may see, it says 2005, we need to change it to 2007

Lets highlight the Copyright text: Copyright John Doe 2005

Now lets go to the Main Menu and select Edit/Find and Replace

The Find and Replace window will pop up:

Now, we do not want to manually do it in each page, lets Dreamweaver make it for us.
So, lets choose the following Options:

Find In: Entire Current Local Site
Search: Text
Find: Copyright John Doe 2005
Replace: Copyright John Doe 2007

Then click over Replace All

After that Dreamweaver pops up a new box asking if we are sure to replace all matches.
Click: YES

Now, Dreamweaver will show us all the html files that have been changed: