# Particle Concept
In the heart of the particle simulation is the
ParticleSystem which controls the shared timeline. A scene can have several particles systems, each of them with an independent time-line. A particle is emitted using an
Emitter element and visualized with a
ParticlePainter, which can be an image, QML item or a shader item.
An emitter provides also the direction for particle using a vector space. Particle ones emitted can’t be manipulated by the emitter anymore. The particle module provides the
Affector, which allows manipulating parameters of the particle after it has been emitted.
Particles in a system can share timed transitions using the
ParticleGroup element. By default, every particle is on the empty (‘’) group.
ParticleSystem- manages shared time-line between emitters
Emitter- emits logical particles into the system
ParticlePainter- particles are visualized by a particle painter
Direction- vector space for emitted particles
ParticleGroup- every particle is a member of a group
Affector- manipulates particles after they have been emitted