Baking particles means freezing the particle stream, including all its modifiers. This can be useful for several reasons:
To bake the particles, select the emitter in the Object Manager, choose the Bake Particles command, set the parameters in the Bake Particles dialog as desired (see below) and click OK. A Baked Particles icon will appear in the Object Manager, to the right of the emitter.
Enable the Emitter and select the Bake Particles command. In the dialog window that opens, enter the length of time for which the particle stream should be baked using the From and To values. The Project length is entered here by default. Modifying these values will have no effect on the particle stream.
This parameter defines how many animation samples the baking will take per frame. For example, if you set the value to 2, the baking will sample the animation every half frame. In general, higher values lead to more physically correct results, especially with fast-moving particles. Keep in mind that the scene’s file size will increase if you increase the Samples Per Frame value.
Here you can choose how frequently (in frames) the particles will be baked. For the most accurate results, set the value to 1, which will result in the position being baked for every single frame. With higher values, the positions will have to be interpolated between the baked (saved) values. Keep in mind that the scene’s file size will increase if you lower the Bake Every x Frames value.
You cannot edit the settings that were used to bake the particles. If you need to re-bake the particles — for example, because you have increased the project length — first delete the Baked Particles icon in the Object Manager, then bake the particles again.