Kotlin is a general-purpose programming language originally developed and unveiled as Project Kotlin by JetBrains in 2011. The first version was officially released in 2016. It is interoperable with Java and supports functional programming languages.

Kotlin is used extensively for Android apps, web application, desktop application, and server-side application development. Kotlin was built to be better than Java, and people who use this language are convinced. Most of the Google applications are based on Kotlin. Some companies using Kotlin as their programming language include Coursera, Pinterest, PostMates among many others.

Level: Intermediate to advanced

Skills Needed: Prior experience with programming languages, particularly Java

Platform: Web, Mobile, Desktop, Server

Popularity Among Programmers: Increasingly popular; used for Android applications

Benefits:
Less code-heavy than Java and other languages;
Relatively easy to adopt
Fully compatible with Java

Downsides: Fluctuating compilation speed; no static keyword in Kotlin

Degree of Use: Widely used; highly applicable