I want to start a site (help)

Drop shipping is basically where the inventory doesn't touch your premises and the manufacture or supplier ships the order directly to the buyer. It's a bit trickier to make a profit with it, but will lower your overhead considerably.

Yes, as others have indicated, dropshipping simply means the wholesaler (manufacturer or distributor) is willing to sell to the retailer (YOU) and then ship direct to the customer.

The wholesaler (preferably the manufacturer of the products) gives you permission to list their products on your website (online store) and you sell them at retail (i.e. $100 for an item). When the product sells, you collect the cash from the customer and send the dropshipper (wholesaler) the customer's shipping info. The "dropshipper" then charges you the "wholesale price" (i.e. $70 for the item) and sends the item direct to YOUR customer. You keep the difference between what you collected and what they charged you (i.e. $30 in this example).

This tutorial explains the concept in more detail and actually has a graphic that shows you how it works visually.

FYI, do NOT let anyone convince you that dropshipping doesn't work or is a scam. The only people that think that are folks that have been conned by retailers posing as dropshippers (you will find THOUSANDS of them by doing Google searches). I assure you dropshipping is legit and works because I've made hundreds of thousands of dollars over the past ~10 years using it. You just have to know how to find a legit wholesaler that will dropship for you in order to make it work!

Pros:
-Reduce upfront costs and commitments (no inventory-carrying cost)
-Reduction in cost of receiving, storing and shipping
-Possible location shipping advantages

Cons:
-Usually stocking retailer pays less (can increase your COGS)
-Problems with orders are more difficult to sort out
-Higher costs over having the inventory yourself
-Can limit product selection