In chemistry, metals are the majority of the known elements (even if the seven metalloids are not counted as metals). The known metals are (from http://chemicalelements.com/):
- Alkali: lithium, sodium, potassium, rubidium, cesium and francium
- Alkaline earth: beryllium, magnesium, calcium, strontium, barium and radium
- Transition: scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, mercury, rutherfordium, dubnium, seaborgium, borium, hassium, meitnerium, ununnilium, unununium and ununbium
- Other: aluminum, gallium, indium, tin, thallium, lead and bismuth
The metalloids are: boron, silicon, germanium, arsenic, antimony, tellurium and polonium
Blacksmiths are interested in the malleable metals (copper, iron, etc.), while automobile engine manufacturers are interested in lightweight yet high-impact-resistant metals (aluminum, titanium, etc.). The metalloids (especially silicon) are often used as semiconductors, which is the foundation of all modern computing equipment. Osmium and iridium are known for their extreme specific gravity (a cubic foot of either weighs over 1400 pounds). Lead is rather infamous from the extensive studies of alchemy in days of old; more recently it is used for common plumbing pipes. Platinum, silver and gold are 'precious metals' because of their relative rarity and pleasing appearance. Gold is also used in computing equipment for contacts between 'pluggable' parts because of it's good conductivity.
In short, metals are a significant defining quality of this physical world. Whether for swords in battle, for nutrition in the form of vitamins, or protective casing surrounding a computer's innards, metals add a lot to our lives every day.