Ink is a colored liquid used for writing, drawing, or printing. When you write with a pen, you're using ink that flows onto paper and dries there permanently. Printers spray tiny droplets of ink to create text and images on paper.

For thousands of years, people have made ink from different materials. Ancient Chinese and Egyptian scribes mixed soot with water and tree gum to create black ink for writing important documents. Squid and octopuses produce their own ink, squirting dark clouds into the water to confuse predators while they escape. Today's inks come in countless colors and types: fountain pen ink that flows smoothly, permanent marker ink that won't wash off, and even invisible ink that only shows up under special light.

The word also appears in tattoos, which use ink injected under the skin to create permanent designs. When someone says a document needs your signature, they might ask you to “put ink to paper.” Newspapers were once called “the ink-stained press” because printers' hands got covered in ink from the printing machines. If a deal is final, people say it's in ink, meaning it can't be easily changed or erased.

As a verb, to ink means to cover something with ink or to sign your name. An artist might ink a drawing, or a player might ink a contract.