What possible states can channels occupy during their use or operation?

Channels in Go can be in the following states:

• Open: the channel is available for sending and receiving data.
• Closed: the channel is closed using the close() function. After closing, data cannot be sent, but already sent values can still be received until the channel is empty.
• Blocked: a goroutine trying to send or receive data may be blocked if the channel is full (for buffered channels) or empty (for unbuffered channels).

Example:

ch := make(chan int, 1) // buffered channel
ch <- 1                 // send value
close(ch)               // close channel

v, ok := <-ch           // receive value, ok == true
v2, ok2 := <-ch         // channel is empty, ok2 == false

Thus, the channel's state affects the behavior of send and receive operations.