Good conductors of heat and electricity
These are four primary characteristics of metals, but there are many others as well.
Metals tend to exhibit luster; that is, they appear to "shine" due to how light interacts with their surfaces.
Metals tend to exhibit malleability, which means they can be deformed under compressive stress; i.e. they can be compressed into thin sheets.
Similar to their malleability, metals also tend to exhibit ductility, which contrarily is their ability to deform under tensile stress. That is, they can be stretched into a thin wire.
Another major characteristic of metals is that they exhibit great electrical and thermal conductivity. Their solid structure allows for an easy flow of electric current through it, and heat energy to pass through it more quickly.