# You can use version control to restore **any** committed version.
+# How else can version control help?
+# What if you're collaborating on a book with someone else?
+# You each have a copy of the book.
+# Your friend makes a change to chapter 2.
+# How do you get that change into your own copy?
+# Copy the entire file that holds chapter 2?
+# What if you made your own changes to chapter 2?
+# Copying the file over would overwrite your changes.
+# You **could** ask them what they changed, and make those changes in your own copy by hand.
+# It's 2010, we have computers now.
+# They can do this kind of work for us…
+# **If** you're both using version control.
+# You make some changes to your book and "commit" those changes.
+# Meanwhile, your friend is doing the same thing.
+# You can "pull" your changes from their computer onto yours.
+# Now you can "merge" their changes with yours.
+# As long as you haven't both changed the same line, the computer can automatically combine their changes with yours.
+# Instead of spending 15 minutes with your friend figuring out what you both changed, you'll spend 10 seconds "merging."
+# We all have better things to do than trying to figure out what changes we made.
+# Let's all use version control to do the busywork for us.
+# I haven't talked about **how** to use version control.
+# Unfortunately we don't have enough time to do it right now.
+# There are two main version control systems that are popular right now.
+# It doesn't matter which one you use.
+# Pick the one you prefer.
+# You'll probably find another one called "Subversion" or "SVN."
+# Mercurial and Git are both far better.
+# Come talk to me if you want to know why.