I don't think anyone's provided the basics yet, so let's start there:
Disney Vacation Club (DVC) is Disney's timeshare. It's a points-based timeshare, meaning that owners are alloted a certain number of points per year, and they use those to 'pay' for their resort stays. Each room type at a DVC resort 'costs' a certain number of points per night. Those point requirements also vary with the seasons, so it takes more points to book a room during, say, Christmas week, than it would to book a room in September.
When people say 'renting points', it's kind of a misnomer. What actually happens is that you arrange with a DVC owner for them to make a reservation for you. You total up the number of points required, and you pay by the point. Often, this ends up being significantly less costly than booking the same room with Disney would be.
In a sense, it's like renting someone's beach house at the shore. You're making a business arrangement with another individual to use their timeshare, for which you pay them.
You can find owners looking to rent on our DVC Rent/Trade board, or through a service that matches owners and renters like DVC By Request.
Important differences between renting points and booking a room through Disney:
As I mentioned above, this is a private transaction. Disney is not involved, except that you're staying at a Disney resort. If anything goes wrong with the transaction, Disney cannot and will not help you.
The owner retains control of the reservation at all times, even though it's in your name. Any changes - adding requests, adding the dining plan, etc - must be done by the owner.
Consider it to be a final transaction. Changing your dates, your room type or your resort will probably not be possible. If you have to cancel, you will probably not get a refund, since DVC's cancellation policies are complex, and the owner may lose their points if you cancel.
Since it's a timeshare, housekeeping will be limited. If you want daily housekeeping, you can pay for it out of pocket.
Since you're not booking through Disney Reservations, you are not eligible for
free dining or any other discounts and promotions. You'll have to run the numbers and see what's the better deal, if a promotion is offered during your dates of stay.
Phew, I think that's the highlights. Now hop on over to our
Rent/Trade board and read through the stickies at the top of that board to get the details.