The number of atoms of each element on the reactants' side (left side) of the equation is equal to the number of atoms of that same element on the products' side (right side) of the equation.

Here's why this is important:

* Conservation of Mass: Chemical reactions don't create or destroy matter; they just rearrange it. Balancing ensures that the total mass of the reactants equals the total mass of the products.

* Accurate Stoichiometry: Balancing gives you the correct mole ratios of reactants and products. This is crucial for predicting the amount of product you'll get from a given amount of reactant.

* Understanding Chemical Processes: A balanced equation provides a visual representation of the rearrangement of atoms during a chemical reaction.

Example:

The unbalanced equation for the combustion of methane is:

CH4 + O2 → CO2 + H2O

To balance it:

* Carbon: 1 carbon on each side (already balanced)

* Hydrogen: 4 hydrogen on the left, 2 on the right. Add a coefficient of 2 in front of H2O:

CH4 + O2 → CO2 + 2H2O

* Oxygen: 2 oxygen on the left, 4 on the right. Add a coefficient of 2 in front of O2:

CH4 + 2O2 → CO2 + 2H2O

The balanced equation is:

CH4 + 2O2 → CO2 + 2H2O

Now, both sides have 1 carbon, 4 hydrogen, and 4 oxygen atoms.