Debt Purchasing?

I've heard about people buying other people's debt as an investment? How does this work and why is it a good investment? Perhaps someone could direct me to a website of some sort if it's a long answer or you can't answer it yourself.
Thanks

maybe you are talking about bond investing. find out here:
http://www.stock-investment-made-easy.co...

it explain about what is bond, how it works, and how it performs as compared to stock market.

You may have a slight misconception. This has nothing to do with the debtor. Let me give you an example. You are buying a house and the seller agrees to take your note as partial payment. You owe the seller money and are repaying the note monthly. That is your debt. The seller has an investment in your note. Now the seller needs cash so he decides to sell the note.

He finds a buyer who is willing to invest in your debt. The buyer buys the note. Now you are making payments to the new owner of the note. Your situation has not changed. The original investor in your note sold it to another investor.

Investors buy these debts in order to earn interest income. Usually the original investor has to discount the note in order to sell it. For example, you still owe $5,000 on the note and are paying 7 percent interest. The buyer of the note is not satisfied with 7 percent interest so he offers to buy the note for $4,500. The $500 discount increases his return on the investment. You still owe $5,000 on the note and continue paying 7 percent.