What does a fire rod do on BBQ grill?

It seems you're asking about a fire starter, not a "fire rod."

Fire starters are tools used to ignite charcoal or wood in a barbecue grill. They come in various forms, such as:

* Charcoal lighter fluid: A flammable liquid that is poured onto charcoal and ignited, starting the fire quickly. However, it can impart a chemical taste to food and is not recommended for grilling.

* Fire starters: These are small, flammable blocks or cubes made from compressed sawdust or other materials. They are placed on top of the charcoal and lit, starting the fire.

* Electric starters: These devices use a hot coil to ignite the charcoal. They are considered safer than lighter fluid but may be slower.

* Chimney starters: These are metal cylinders with a base and a grill. Charcoal is placed inside, and a lit piece of paper or fire starter is placed underneath. The heat from the fire starts the charcoal burning.

There's no such thing as a "fire rod" commonly used for grilling.

Let me know if you have any other questions about barbecue tools or techniques!