Protoss often proxy their tech building early on for an attack, and Terran lose the game immediately when they are not prepared well. This post discusses the response toward the two mainstream proxy tech builds.
There is actually an interesting metagame for proxy now for TvP and TvT.
Arnaud was discussing with me about Pylon Overcharge rushes in the early game, and I thought it is an interesting topic to post. This post is about identifying the attack and defending it.
The earlier post regarding how to defend against proxy Oracle sets the basic of what should be done in that situation. Recently, Flash added something on top of the standard reaction discussed previously, and I think it is worth discussing.