What is the purpose of the next() function in Express?

The next() function is used to pass control to the next middleware function in the stack. If the current middleware does not end the request-response cycle, next() must be called; otherwise, the request will hang. Example:

app.use((req, res, next) => {
  console.log('Middleware 1');
  next(); // Pass to next middleware
});
app.use((req, res) => {
  res.send('Hello from Middleware 2!');
});