A volt is the unit we use to measure electrical pressure — how hard electricity is being pushed along a wire. If you think of electricity as water in a pipe, volts are the water pressure, while amps measure how much is actually flowing. The higher the voltage, the harder the push, which is why a 220-volt wall socket is dangerous and a 1.5-volt battery in a remote control is not. You meet the word mainly as a number plus the unit: a 9-volt battery, 110 volts, a 5-volt charger. Written short it is V with a capital letter and no dot — 12V, 240 V — and by convention the unit name is lower-case (volt) even though the letter symbol is capital, because it honours a person. Everyday electrical talk uses it constantly: travellers ask what voltage a country runs on, since Taiwan uses 110 volts while most of Europe uses 220 to 240, and plugging the wrong device in can destroy it. The related noun voltage means the number of volts, and is what people usually say when speaking generally: "check the voltage", not "check the volts". Note that after a number used as an adjective before a noun, English writes it singular and hyphenated: a nine-volt battery, not a nine-volts battery.