Concept:
Food fortification is a public health strategy used to improve nutritional quality of food.
Step 1: Some foods may lack essential nutrients.
Step 2: Fortification means adding essential vitamins or minerals deliberately.
Step 3: Examples include iodized salt and iron-fortified flour.
Step 4: It is not the same as adding preservatives or removing contaminants.
\[
\boxed{\text{Deliberate addition of essential nutrients to food}}
\]