What is Erlang?
Some of Erlang's uses are in telecoms, banking, e-commerce, computer telephony and instant messaging. Erlang's runtime system has built-in support for concurrency, distribution and fault tolerance. OTP is set of Erlang libraries and design principles providing middle-ware to develop these systems.
Erlang is a tool in the Languages category of a tech stack.
Why developers like Erlang
Real time, distributed applications
Works as expected