Human civilization can be mapped through its alloys:

• Bronze (copper + tin) — discovered around 3300 BCE, ending the Stone Age. Harder than copper, it held a sharper edge for weapons and tools.
• Steel (iron + carbon) — the backbone of the Industrial Revolution and modern construction.

Newer alloys keep pushing engineering further. Titanium alloys pair high strength with low weight and corrosion resistance, which makes them essential in aerospace.