Fortification means making something stronger or harder to attack. When medieval kings built stone walls, towers, and moats around their castles, they were creating fortifications to protect against enemy armies. These defensive structures turned ordinary buildings into strongholds that could withstand sieges lasting months or even years.

Throughout history, cities built fortifications like thick walls, watchtowers, and gates to defend themselves. The Great Wall of China, Roman forts across Europe, and the walls of medieval cities like Carcassonne in France are all famous fortifications that still stand today.

Fortification applies beyond warfare as well. When you add extra vitamins to breakfast cereal or orange juice, that's called fortification too: making food more nutritious. Engineers fortify bridges and buildings to make them stronger against earthquakes. When you study hard before a big test, you might think of yourself as fortifying your knowledge, building up your understanding so it can withstand tough questions.

The related word fortress means a heavily fortified place, usually a castle or military stronghold designed to be nearly impossible to capture. A fort is a smaller fortified position, like the frontier forts American soldiers built in the 1800s.