Last month, multi-billionaire megainvestor Warren Buffett confirmed that Berkshire Hathaway (NYSE:BRK-A)(NYSE:BRK-B) was upping its buyback authorization and would begin buying back stock at prices anywhere up to 1.2 times book value -- prompting a lot of investors to respond: "Great! But, uh, what exactly is book value?"

Technically speaking, book value is defined as: "The net asset value of a company, calculated by total assets minus intangible assets (patents, goodwill) and liabilities."

But if that definition just leaves you asking again, "so, um, what does that mean?" then maybe this will help. You know the old expression about a sum being greater than the whole of its parts, right? Well, the price of the "sum" for Berkshire is the price of the stock -- currently 1.2 times the price of the parts. And the price of those "parts" -- that's book value.

...and parts
To firm up the picture even further, though, we thought we'd take a closer look at Berkshire for you, and sketch out for you in a bit more detail exactly what Berkshire's various parts are -- and how they've grown in value over time. Here they are, in three simple illustrations.

First, the business. Most folks, when they hear the name Berkshire Hathaway, probably think first of the GEICO subsidiary, and its famous gecko mascot. But Berkshire is a whole lot more than just GEICO. In fact ... see if you can spot the gecko's hangout among all these piles of revenue.

Now, let's take a look at a few odds and ends of other companies that Buffett has picked up and tucked away within Berkshire's portfolio over the years. There are literally dozens of them, so here we'll show you just the biggies:

And finally, here's a quick glimpse of how the value of all the above -- plus a little bit of Buffett magic to make that value grow -- has increased over time relative to the S&P 500. Hint: If you had started with an investment value of $10,000, 46 years in "the stock market" would have transformed that into $639,700 through 2011. Put the same start-up capital in Berkshire stock, though, and you'd have ended up with more than $51 million.

Rich Smith has no position in any stocks mentioned. The Motley Fool recommends Berkshire Hathaway. The Motley Fool owns shares of Berkshire Hathaway. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.