Debate with strangers. One topic, two sides, two people.

Open the list of debate topics and pick one. Choose your side. If someone is already waiting on the other side, you are matched at once and the debate begins. If not, you wait in the queue for that side and you are told when an opponent joins. You can leave the queue at any time.

If you would rather not wait, start a turn-based debate. You open a challenge with your side, and the debate begins when someone takes the other one. You can also invite a particular person to debate a topic with you.

A live debate is a chat room with two debaters and any number of spectators. Messages, voice notes and images appear in real time. It suits a focused half hour.

A turn-based debate has six written turns, with 24 hours for each. You can edit your latest argument until your opponent has answered it. It suits people in different time zones and people who want to think before they write.

A stranger owes you nothing, so earn their attention. Begin with a clear claim. Give one good reason before you give three weak ones. Quote what the other person said before you answer it, so they know you read it. Ask a real question when you do not understand a point. When you are shown to be wrong on something, say so; it is the quickest way to be believed on the rest.

When a debate ends, each person has 24 hours to rate the other on politeness, thoughtfulness, how easy they were to talk to, honesty and open-mindedness. Ratings are anonymous, and after you have talked or debated with at least three different people your reputation shows on your profile. People who debate well and treat opponents fairly become easy to recognise.

The best topics have two defensible sides and a clear question. Whether the workweek should drop to four days, whether social media should be banned for under-16s and whether nuclear power is the answer to climate change are all topics where thoughtful people disagree for good reasons. You can browse the full list by category, or propose a topic of your own, which appears after a person on our team approves it.

Waiting is part of debating a stranger. In a live debate you stay in the queue until someone joins the other side, and you can leave whenever you like. In a turn-based debate each turn has a 24 hour limit. If a turn is missed, the debate ends and counts as a forfeit by the person who missed it, so you are never left waiting without an end.

A finished debate is yours to look back on. Rate your opponent, and notice what you were rated on yourself: politeness, thoughtfulness and open-mindedness matter as much as winning the point. Many people find the second debate on a topic is much better than the first, because they know the strongest objections.

Messages are not screened before delivery. Inside a debate you can report a message or a person with the flag icon and block anyone you do not want to hear from. A person on our team reviews reports, and serious violations lead to suspension or a permanent ban. People under 18 debate only people under 18, and adults debate only adults.

You need a free account and you must be at least 16 to debate. Anyone can watch public debates without an account.