Disk Utility is a function of OS X that, if you're lucky, you may never have to use. However, it's a good idea to have an understanding of what Disk Utility is all about if you should ever need to use it. Here is an excellent article from Macworld on Disk Utility that you might want to read and retain for future reference. On page 2 of the article is a paragraph -- Fix startup problems -- that you may want to copy and print a document of what to do if your Mac won't start up. This probably won't happen, but if it should it's nice to know what to do.
Comment by John Carter
On Page 2 it starts out talking about the older Disk Utility that had Verify Disk and Repair Disk Permissions. That is quite confusing to any reader because on page 1 it clearly states that these two functions were removed from Disk Utility.
In fact, everything on page 2 is about the older Disk Utility and has nothing to do with the new Disk Utility, including how to fix the startup disk. In my view, that second page link is a mistake - it goes to the wrong page.