spawn to make something work in the background without blocking the main execution.spawn creates a lightweight thread called Fiber. Fibers are very cheap to create and you can easily create tens of thousands of Fibers on a single core.spawn to make stuff work in the background but how do we get something back from a Fiber.Channels come to play.Channel is a channel between a sender and the receiver. Therefore a Channel lets each other communicate with send and receive methods.Channel with Channel(String).new. Note that we are creating a Channel which will send and receive messages with type of String.spawn. You might ask ‘Why are we sending message in the background?’ Well, send is a blocking operation and if we do that in the main program we gonna block the program forever.channel.send "Hello?". Now that we know why we use spawn to send a message let’s continue.spawn. Then we receive it back with channel.receive. In this example the message is Hello? so this program prints Hello?and then finishes.