Particles

Particles are a type of Entity in Minecraft; they are graphical effects. The particles always seem to face the player and will usually disappear after a short period of time. They only appear from another entity such as fire.

You can reduce the amount of particles visible in the Options menu. These options range from All to Minimal. All renders all particles, decreased renders half the amount of particles, minimal renders no particles.

Types of Particles
In Minecraft's code one can find a variety of particles. To help coders or curious players, the types of particles and their coding names in the game's code are displayed below. Particles collide with solid blocks and are slowed down by cobwebs, but are unaffected by other entities. Each particle texture is 8x8 pixels.

Blocks, entities, and events that use particles
Particle names in italic will always be shown, even if the "Minimal" particle setting is used.

Particle-detector


A Particle detector activates a redstone output, whenever a particle drops near from the detector. Every particle (block-breaking-particles,snowballs,splash-potions,eggs,etc..) is detectable. Particle detectors do not work in SMP, signifying that this no longer works past Minecraft 1.3.

Experimentation reveals that as of Minecraft 1.2.5, a detector rail will trigger when a particle, mob, or any other entity except an arrow touches it if there is a minecart slightly overlapping it, which is most easily achieved if the minecart is on a downward slope and pushing into a fence post or fence gate above the powered rail, as shown in the video. The pressure plate seems to be irrelevant.

The detector rail will stay on until the minecart is no longer touching it, so a fence gate is preferable to a fence post, as the detector rail instantly powers and opens the gate, releasing the minecart. However, this requires some sort of minecart return mechanism, also as shown in the video. The video uses a closed loop, which can break if a player or mob pushes the minecart the wrong way, as the detector rail will open the fence gate and allow the minecart to continue moving. A simpler solution is to use a linear track, with powered rails reversing the direction of the minecart at both ends.

Note that the powered rail on the bottom right does not need to be powered with a redstone torch, as the detector rail powers it when the mechanism is triggered.

Trivia

 * Most particle colors can be changed using texture packs, however the color of smoke particles used in redstone, portals, and Endermen can't be changed without mods or third-party tools.
 * The rain particles affect the rain sound.
 * Mobs spawned using a Monster Spawner emit smoke particles when spawning.
 * The particles generated while sprinting are parts of textures extracted directly from the terrain.png file in the minecraft.jar folder. This is shown by the fact that gray particles are emitted when sprinting on leaves or grass.
 * The smoke from the beacon effect is more transparent.
 * Particles are slowed when passing through a Cobweb.
 * "footstep" is unused in the game at this time.