You've probably read that the market value of Apple, Inc. is worth a trillion dollars. It's difficult to visualize what a trillion is, but here are some examples that might help.
Go back a billion seconds and you'd be in 1995; go back a trillion seconds and you'd be around 30,000 B.C.; a dollar bill weighs about a gram, thus a trillion of those dollar bills would weigh 2.2 billion pounds;
It's estimated that all the money in circulation today in the U.S. is about a trillion dollars.
Some years ago Gizmodo put together a conceptualization of what a huge pallet of a trillion dollars would look like. Take a look here, and remember -- each pallet is $100 million.
This might be more understandable: if you'd invested $10,000 in Apple stock 10 years ago you'd have $92,000 today, excluding dividends.