Category - Home Selling Questions - General Home Selling FAQ's
An offer based on something else happening. The most common type of contingent offers are House to Sell (the buyer must first sell their existing home before they can buy yours) and Contingent on Financing (buyer must be able to secure financing by a certain date). If the contingency hasn't been met the parties can go their own separate ways and earnest money will be returned.
References
Courtesy of HomeOwners Advantage and link that to their entry in the wiki which is at HomeOwners Advantage