C C++ C#

C Programming Language
C is a general-purpose computer programming language. It was designed to be compiled to a machine language (a low-level computer language), so it is fast. Learning C helps us understand a foundation of programming such as an operating system or other programming languages because many of them build off of it.

What Can You Do With C ?
Operating systems
Embedded system applications
etc

C++
C++ was developed as an extension of the C programming language. Its advantage is the feature of object-oriented programming, which allows code to be reusable and makes a program more reliable.

What Can You Do With C++ ?
Operating systems
Web browsers
Games
GUI based applications
Database software
etc

C#
C# is a high-level, object-oriented programming language created based on C++ and Java. Since it was created by Microsoft, it is string at builing Windows applications and games.

What Can You Do With C++ ?
Game development using Unity
[Example] Microsoft official website, Skype website