MQTT protocol

[BlogRahul]

I have  heard a lot about the MQTT protocol I am trying to understand why MQTT protocol used in IoT insted of HTTPs.

[Berni]

MQTT consumes less data traffic, is simpler to implement for a microcontroller and allows bidirectional communication (so when someone publishes new data everyone who wants it instantly gets the data forwarded to them, in http you have to poll the server)

[Siwastaja]

Hypertext Transfer Protocol aka. HTTP is designed for serving web pages from a single server to multiple clients.

MQTT is designed for sending small measurement data packets in whatever (usually efficient) format to a central server, which then further distributes the messages to the subscribers.

Quite a different use case.

[jancumps]

Yes.
MQTT is closer to a Java Message Server and the likes, where you can publish messages, and subscribe to messages.  You talk to a distribution service, and indicate a subject (topic). You don't (have to) know the final interested party/ies.
HTTP is closer to a remote procedure call. You talk to a single end point.