C & C++

C is probably the oldest and popular programming language and is the
root of other programming languages such as C#, Java, and JavaScript.
C++ is an enhanced version of C. Many developers today skip learning C
on its own, while others think learning C first provides a valuable
foundation for C++ development. Both languages are widely used in
computer science and programming. 

C and C++ developers can make use of compilers for a wide variety of
platforms, making applications developed in these languages largely
transportable. Both C and C++ are considered high-performance languages.
As such, they are widely used in developing applications where
performance is a critical issue, such as client/server applications,
commercial products like Firefox and Adobe, and video games.