How do everyday machines decide?
Answer first
Every day, machines make small decisions for you. A spam filter decides which emails you see. Autocorrect decides which word you meant. Each page here explains one everyday machine: what it decides, what it looks at, how it learns its rule and where it goes wrong. Then you try a small version yourself.
Last reviewed: 24 October 2026 1 min read
Machines
| Machine | What it decides | What it looks at |
|---|---|---|
| Spam filter | Is this email spam? | content, sender, links |
| AI detector | Was this made by a machine? | word patterns, learned examples |
| Photo tagging | What is in this picture? | patterns of color and shape |
| Map routes | Which route is fastest? | roads, traffic, closures, tolls |
| Autocorrect | Which word did you mean? | letters, common words, nearby words |
| Face unlock | Is this the phone's owner? | saved face, new picture, features |
| Translation | Which words fit in the other language? | words, context, word order, fluency |
| Video recommendations | What should this viewer watch next? | past viewing, title, video length |
| Voice assistant | Did someone just say my name? | the sound pattern of speech |
| Chatbot | Which word comes next? | words so far, learned patterns |
| Email sorting | Which tab does this email go in? | sender, what it says, your moves |
| Plant identifier | What plant is this? | leaves, flowers, bark, photo quality |
| Robot vacuum | Keep going, turn or stop? | bumper, floor sensors, battery, map |
| Search autocomplete | Which searches should I suggest? | your letters, popular searches, freshness |
| Smart thermostat | When should it heat or cool? | time, temperature, who is home |
| Weather forecast | Will it rain? | stations, balloons, satellites, physics |
Explore
- How does a spam filter decide what is spam?A program that scores each incoming email and moves the ones that look like junk or scams out of your inbox.↗
- How does an AI detector decide who wrote something?A program that scores writing or pictures for how machine-made they look, and flags the ones above a line.↗
- How does photo tagging decide what is in a picture?A program that looks at a picture and adds word tags to it, such as "dog" or "beach".↗
- How does a map app decide the fastest route?A program that gives every road a cost, such as travel time, and finds the route from start to finish with the lowest total.↗
- How does autocorrect decide which word you meant?A program that spots a word that looks mistyped, lists real words close to it and swaps in the one that scores best.↗
- How does face unlock decide it is you?A program that compares the face in front of the camera with the owner's saved face and unlocks only if they match closely enough.↗
- How does a translation app decide which words to use?A program that turns a sentence in one language into another by scoring possible translations and picking the best one.↗
- How does a video app decide what to show next?A program that picks a short list of videos from a huge library, scores each one for a viewer and shows the top few next.↗
- How does a voice assistant decide you said its name?A program in a speaker or phone that listens for its name, then records what you say next and turns it into words.↗
- How does a chatbot decide what to say next?A program built on a language model that writes a reply by predicting one likely next word after another.↗
- How does email sorting decide which tab an email goes in?A program that puts each wanted email into a tab, such as the main inbox, promotions or updates.↗
- How does a plant identifier decide what plant it is?A program that looks at a photo of a plant, guesses its name and gives the guess a confidence score.↗
- How does a robot vacuum decide where to go?A small floor-cleaning robot that reads its bumper, floor and battery sensors and follows rules to keep going, turn or stop.↗
- How does search autocomplete decide what to suggest?A program in a search box that guesses the rest of your search from the first letters you type and shows a few suggestions.↗
- How does a smart thermostat decide when to heat or cool?A program that learns when a home is busy or empty and picks when to heat or cool it.↗
- How does a weather forecast decide if it will rain?Computer models that use measurements of the air today to work out the weather ahead, giving a chance of rain from 0 to 100 percent.↗
Questions
A machine decision is a choice a computer program makes by following a rule, such as "move this email to spam" or "unlock the phone". Some rules are written by people. Others are learned from examples.
No. They follow rules and patterns. Some rules come from many examples, so the machine can be right often and still make mistakes no person would make.