How is data transmitted through a non-buffered channel? Does it have a buffer?

In Go, an unbuffered channel does not have an internal buffer, so data transfer through it occurs synchronously. This means that the sending goroutine blocks until another goroutine receives a value from the channel, and vice versa — the receiving goroutine blocks if there is no value in the channel.

Thus, an unbuffered channel is used for synchronization and direct data transfer between goroutines without intermediate storage.

Example:

ch := make(chan int) // unbuffered channel

// Sending goroutine
 go func() {
    ch <- 42 // blocks until someone reads
}()

// Receiving goroutine
val := <-ch // blocks until a value appears
fmt.Println(val) // 42

If the channel were buffered, sending could occur without blocking until the buffer is full.