Example 1
Antarctica isn't just the coldest place on Earth; it's also the driest.
In Antarctica's Dry Valleys region, it hasn't rained in over 2 million years. Seriously. In this example, the semicolon is used to join two complete sentences that are very closely related in idea.
Example 2
The cafeteria offered a choice of ham, turkey, or salami sandwiches; potato chips, French fries, or mixed greens; and milk, soda, or juice.
This example makes us wish we hadn't skipped lunch. Here, semicolons are used to separate the list of various menu options by type. This makes the information much easier for the reader to digest. Hey-o!