Pressure plates are non-solid Minecraft blocks that detect items, players, mobs, and other entities and form integral components of redstone machinery.
Depending on the material the pressure plate is made from, it is capable of detecting and omitting different things in Minecraft. Regardless of what is detected, pressure plates emit redstone signals.
Weighted pressure plates can also have a delay in their redstone signal deactivation, allowing players to create redstone machinery that is based on this delay in interesting time-based aspects.
Considering pressure plates are quite easy to craft and use, their effectiveness really comes down to a player's imagination and creativity with how they operate.
Minecraft: Crafting and using different pressure plates and how they differ
Creating pressure plates is quick and easy in Minecraft. All they'll need are appropriate materials and a crafting table. The recipes and uses for the different pressure plates available in-game can be found below:
Stone Pressure Plate
Requires two stone blocks. These pressure plates, when placed, will only detect players and mobs that step on them.
Wooden Pressure Plate
Requires two wooden plank blocks of the same type. These pressure plates will detect all entities that make contact with them.
Polished Blackstone Pressure Plate
Requires two polished blackstone blocks. These pressure plates operate in the same manner as stone pressure plates.
Heavy Weighted Pressure Plate
Created with two iron ingots. This plate can detect all Minecraft entities and its signal strength increases as more entities make contact with it. Heavy plates in particular measure entities in groups of 10.
Light Weighted Pressure Plate
Created with two gold ingots. These plates detect all entities and their signal increases based on each entity that makes contact with them. Unlike the heavy plates, they merely count individual entities instead of grouping them.
Once Minecraft players have crafted their pressure plate, all they need to do to place it is to right-click or the use button with the block in their hand. Pressure plates can be attached to the top of any completely solid and opaque block in the game. They can additionally be placed atop hoppers, fences, and upside-down slabs and stairs.
Pressure plates interact with redstone dust wiring as well as redstone machinery blocks. The simplest example of this is placing a pressure plate in front of a door, whereupon the pressure plate will cause the door to open/close based on the state of its activation.
Pressure plates can even be used in rail systems by using them (along with one redstone dust and six iron ingots) to craft detector rails, which are capable of activating upon detection of an entity within a minecart.
When it comes to pressure plates in Minecraft, the name of the game is experimentation.