Questions about redstone contraptions and machinery in Minecraft. For command block contraptions, use the "minecraft-commands" tag instead. Always use this tag together with the "minecraft-java-edition", "minecraft-bedrock-edition" or "minecraft-legacy-console" tag.
Redstone circuits and machines can be used to do Survival-assisting or recreational tasks, from a simple piston door over Rube-Goldberg machines to multiple-kilometer-long quarries that autonomously mine out huge areas of the world.
For more information, see the "Redstone mechanisms" article on the Minecraft wiki.