# Transactions at a Glance — MongoDB

Source: https://www.geekswithgeeks.com/en/mongodb/mongo-transactions

> Multi-document ACID transactions for all-or-nothing updates.

## Multi-document ACID

A **transaction** groups several writes, possibly across collections, so they all succeed together or all roll back.

## Sessions & withTransaction

Start a session, then run operations inside `withTransaction` — it commits automatically or aborts on error.

```javascript
const session = client.startSession();

await session.withTransaction(async () => {
  await accounts.updateOne({ _id: a }, { $inc: { balance: -100 } }, { session });
  await accounts.updateOne({ _id: b }, { $inc: { balance: 100 } }, { session });
});
```

## Use sparingly

Reach for transactions only when multiple documents truly must succeed or fail together — good schema design (embedding) avoids needing them for most cases.