The interviewer asks this question to determine your ability to summarize a topic. A good summary clearly conveys complex information in a few words. Variations include asking you to explain almost anything to someone who doesn’t know about it, or who can’t understand complex concepts.
Good answers to this question use simple examples the listener (in this case the 3 year old) would understand to explain the subject (in this case a database.) Another point is to do your best to exceed the requests’ expectations, in other words explain it in two sentences instead of three.
Toy Box:
“A database is like a toy box where a company keeps important secrets. When they need the secrets, they use a computer to open the toy box and get the secrets.”
Shopping List:
“A database is like a shopping list with lots of things on it – apples, bread, eggs, milk, cereal, bananas, soda, candy. When people want what’s on the list, they go aisle by aisle just like in the store. They’d find bananas and apples in the same aisle.”
Crayons:
“A database is like your crayon box, with all different crayons in there. A computer asks for a color, or a type of color. Then it takes that color from the box, maybe orange and red.”
Teddy Bear:
“Businesses have important things they know, like your teddy bear’s name. They save it in a computer, and then go get it when they need to know the name.”
Some workers feel their boss is a three year old when it comes to really understanding the job, but the question could apply to many types of people as the listener (the person to whom you must explain the concept.)
Explain marketing to a clown:
“Marketing is driving out in your silly car. People are curious about the car, so they watch to see what happens next.”
Explain computers to a primitive person:
“A computer is like a man who remembers all the names of all the people ever born in the village. He has no wife, so he has no babies, but when someone has a baby they come to him, they tell him about their baby, and he chooses a name.”
The answer doesn’t have to be 100% accurate. A 3 year old isn’t going to understand a data base completely, just as a primitive person with no understanding of electricity or machines won’t understand a computer completely. But if it’s plausible that they would understand the example and have a good idea of what you’re explaining, then you’ve answered the question in a way that shows you know how to summarize.
One man was really honest in his answer. “How would I explain a database to my three year old? Honey, that’s something at daddy’s work.”