When you need to transfer money from one place to another, there are a variety of ways to do it. Each one of them has a different cost involved.
Western Union is popular because it is fast, but it is also very expensive. Fees usually reach up into the hundreds of dollars or more for a single transaction. There are also limits as to how much you're allowed to spend, and your transaction (if large enough or to a country that the U.S. doesn't like) will likely be reported to the "authorities".
Imagine if you could move millions of dollars to anyone, anywhere in the world for free... Well, that is the power of Bitcoin.
In fact, on Dec 2, 2014, someone moved more than $80 million USD for less than $0.04. The transaction is publicly visible on Bitcoin's public ledger that forms the backbone of the currency. It occurred in block #332586.
A screen cap from Blockchain.info (the website that allows you to view and search the blockchain) is shown here:
For those of you are still learning, this gives you an idea of what the Blockchain looks like. It is a public ledger of all Bitcoin transactions which can be viewed, searched, and audited by anyone. You will also notice that there is no personal information connected to these transactions. It's anyone's guess who this person is. All we know is that they moved over $82 million USD in the form of 217,517.63438199 BTC and paid less than 4 cents (0.0001BTC) to do it.
That sure beats the hell out of Western Union!