A 1031 exchange can be completed simultaneously by two individuals exchanging property but is most likely to be a delayed exchange. 

In a delayed exchange, an investor/property owner (you) sells a property using a Qualified Intermediary (QI) middleman as a pass-through owner.

The QI holds your funds after you close on your sale and uses them to buy the replacement property on your behalf. Since you never take possession of the proceeds, the transaction is considered a swap and qualifies for tax deferred status.