Playing as Protoss against Terran can be a very difficult game as Terran is so unpredictable and hard to scout. Protoss must know what the enemy is doing so they can build the correct counter units but this is a challenge against good Terran players. This guide will show you how to beat a Terran player 1v1.
The first thing we need to talk about is scouting, the key to winning the game as a Protoss player is using the correct units to counter what your opponent is making. So I recommend building an observer as soon as you can and getting it into the Terran base to see what he is doing.
If the Terran player is using a lot of marines and marauders then build a few colossus, as they will make short work of them, just make sure you also have a bunch of zealots to shield the colossus from too many attacks. If the Terran playing is using thors or tanks then build some immortals as they will dominate the thors and tanks without even taking that much damage. The Terran player may make an air attack with vikings and banshees. When you see this coming just build a bunch of stalkers and they should not have much trouble taking down the banshees. I would not recommend building air units when playing against Terran because marines do decent damage to air units and that alone will be enough to defend against your void ray attack or even a few carriers.
Another thing to watch out for at the start of the game is the reaper attack. To defend against this just make sure you get a few stalkers as soon as you can. If you follow this guide and learn the strengths and weaknesses of your units then you should not trouble beating a good Terran player.