Bio is a short form of the word “biography,” meaning a brief description of someone's life and accomplishments. When you create a social media account, you might write a bio that tells people who you are and what you're interested in. An author's bio on a book jacket typically includes where they live, what they've written before, and maybe an interesting fact or two.

The key word here is brief. While a full biography might fill an entire book, a bio is condensed to just the essentials, sometimes just a sentence or two. A student council candidate might write a bio saying “I'm in fifth grade, I love robotics, and I want to make our cafeteria more eco-friendly.” A musician's bio for a concert program might mention where she studied, what instruments she plays, and notable performances.

The word bio also works as a prefix meaning “life” or “living things.” Biology is the study of living organisms. Something biodegradable breaks down naturally because living organisms can decompose it. A biosphere is a region where life exists. When you see bio- at the start of a word, it usually connects to life or living systems in some way.