A tick in the gaming and game development world refers to a short unit of time which is repeated many times a second. It is usually the period taken to execute the main game loop once. A tick in Minecraft takes up a fraction of a second – that is, many ticks happen every real-world second. However, if your computer cannot keep up, the internal server will skip a certain number of ticks or just extend them to suit its needs. There are three main types of ticks in Minecraft, even though they are all controlled by the same underlying timer:

• Game ticks happen every twentieth of a second (20 ticks per second or TPS). Every game tick:
  • entity positions are updated (recall entities are Newtonian objects with position, velocity and rotation and as thus their properties need to be recalculated often due to external influences like gravity). This includes, but is not limited to the player, all other mobs and dropped items.
  • Player health and hunger are updated and lowered or increased as necessary.
  • Mobs check their surroundings and update their behaviour according to certain, mob-specific rules.
• Chunk ticks happen every game tick (20 TPS) too.
  • A chunk is an area of the Minecraft world 16x16x256 blocks in size. Note 256 is the default build height limit. They are individually generated all in one go by terrain generation algorithms.
  • A chunk section is one of 16 areas of a chunk which is 16 blocks in height, thus making its dimensions 16x16x16.
  • Chunk ticks are applied to a radius of chunks around the player, based on the player’s render distance.
  • For every chunk section inside these chunks, 3 random blocks are chosen (this is modifiable using the /gamerule randomTickSpeed command), for a total of 48 blocks per chunk.
  • A block tick is applied to these 3 blocks. Most blocks completely ignore it, but some use it to do something:
    • Plants grow, for example, wheat will progress to the next stage of development.
    • Fire spreads, if it find a flammable material near it.
    • Farmland hydrates from regular tilled dirt to hydrated tilled dirt (darker colour)
    • Leaves decay and disappear if the wood nearby is gone.
    • Much more, but let’s concentrate on redstone.
• Redstone ticks happen every two game ticks, that is, 10 TPS or every tenth of a second. They control the delay in redstone circuitry – in fact, every redstone component such as a repeater set on minimum introduces a 0.1 second delay. However, there are ways to get around this and reduce the delay to 0.05 and even 0, which we will touch on later on.

It’s important to know about every type of tick so that we can take advantage of them – to create redstone contraptions based on exploiting mob behaviour, for example.