Dichotomous Key
A dichotomous key is a tool used to identify organisms or objects by following a series of choices. The word “dichotomous” means “two parts,” so each step in the key gives two contrasting statements. You choose the statement that matches the organism you are trying to identify, and that choice leads you to the next step. By continuing this process, you eventually reach the name of the organism.
A dichotomous key works like a decision path. At each stage, you compare two features, such as “has wings” or “does not have wings.” These pairs of statements are based on observable characteristics like shape, size, colour, body parts, or behaviour. Because every step has only two options, it becomes easy to sort and identify even very similar organisms.
Scientists commonly use dichotomous keys in biology to identify plants, animals, fungi, or insects. Students also use them in labs, especially in classification topics. The key is reliable only when the characteristics are clear, measurable, and do not overlap.
In short, a dichotomous key helps you identify something by making one choice at a time, narrowing down the possibilities until only one correct answer remains.