A metal is malleable and usually ductile, metals have good conductivity: they also have a lustre, they conduct heat and electricity, and form positive ions.
A simple form of iron is cast iron, but this is less valuable than steel, which is far more useful both for tools and weapons, and also in construction.
Most metals are found as compounds called ores: one ancient source of pure iron ore is bog iron, which was exploited by the Vikings, among others.
Most metals are affected by corrosion, particularly those high on the activity series, though a few like aluminium can be protected by a tough coating of oxide.
Galvanized iron does not rust when it is scratched, but tinplate rusts readily, reflecting the different reactivities of zinc and tin, compared with iron.
Cathodic protection depends on metals having different tendencies to be oxidized: a zinc block attached to a hull will protect a steel ship from corrosion.