The particle render type of a particle object determines how the particles look when rendered. For example, you can display particles as small spheres, streaks, or 2D images (known as sprites) of your favorite snapshot. Once you select the particle render type, you can add attributes specific to the render type to adjust the appearance.
The Streak render type displays moving particles with an elongated tail. This render type enhances the display of objects such as meteors, and it’s often used to create rain. The streak length is based on the velocity of the particle, so if the particles are stationary or moving slowly and the render type is set to streak, you won’t see the particles.