FIRE is the abbreviation for "Fast Interactive Rendering" and describes a real-time render method. The workflow is simple:

The Maxwell FIRE icon.

• Prepare your scene/simulation and apply materials to the nodes.
• Click on the FIRE button in the Render shelf – the → "Maxwell Interactive" panel is opened, and the render starts.
• Now, change the → viewport perspective, → object/mesh/emitter materials, or node positions, and the image will be updated in real-time.

Finally, → lighting and → render quality can also be changed at render time directly:

The Maxwell Scene Preferences icon.

• Render shelf > Maxwell Scene Preferences > Settings tab
• Here you will find several settings for controlling the render's environment.
• Click on "Apply" to see the effect of your settings.
• Once you are happy, click on "OK" to confirm the adjustments.