Yes, C# language currently is a popular language.

The way to measure the popularity of a programming language is by examining the job demand because it reflects what the industries are searching for. Below shows the most in-demand languages of the end of the year 2017 (Putano, 2017).

As we can see that C# is the 3^rd most popular languages from the job websites, signifying its weight in Line of Business applications.

According to Glassdoor, the average C# developer salary, as of April 2018 in the United States, was $79,954. The range extended from $61,000 to a high of $104,000 per annum (Glassdoor, 2018).

Beside from the career prospects and the salary expectations, we can also analyze the number of users of using each language programming languages from GitHub. Here, GitHub is the most suitable choice of data sources because as of June 2018, GitHub reported to have over 30 million users (GitHub, 2018) and 57 million repositories (Firestine, 2017), making it one of the largest host of source code in the world (Gousios, Vasilescu, Serebrenik, & Zaidman, 2018).

Below shows the overall rankings for each language (Frederickson, 2018), we can see that C# is the 7^th most used programming language.

Why so many people are using C#?

1. the mature ecosystem surrounding C#, including
   1. the greatest IDE of all: Microsoft Visual Studio, which also offers
      • a free version - Microsoft Visual Studio Community
      • a Mac version - Microsoft Visual Studio for Mac
      • and even a lightweight, cross-platform version - Visual Studio Code
   2. .NET Framework, and the vast libraries offered by the framework
   3. .NET Core, the open source and cross platform version of .NET Framework
2. C# has a small learning curve (Mashable, 2018)
3. C# is very versatile for developing a multitude of different applications, including
   • Desktop apps
     • WinForms
     • WPF
     • UWP
   • Web servers and clients
     • ASP.NET
     • ASP.NET Core
   • Mobile apps
     • Xamarin
   • Games
     • Unity
4. the language itself still evolving continuously, which gained even more traction with the open source of .NET
   • Roslyn, the C# (and Visual Basic) compiler is open source on GitHub
   • C# language specification is also open source at GitHub, where everyone can suggest ideas and make improvements to the language

Where C# is used?

C# is used in mainly business domain including desktop and web application as stated before (Current Usage of C#). Recently, C# is also getting more and more attention in the following areas:

1. Game development
   • Unity
2. Mobile development
   • Xamarin
3. Cross-platform development
   • .NET Core
   • Xamarin
   • Mono
4. Artificial Intelligence
   • Azure AI Platform
   • ML.NET

References

1. Putano, B. (2017, December 18). Most Popular and Influential Programming Languages of 2018. Retrieved from https://stackify.com/popular-programming-languages-2018/
2. Glassdoor. (2018, July 15). C#.net Developer Salaries (Glassdoor). Retrieved from https://www.glassdoor.com/Salaries/c-net-developer-salary-SRCH_KO0,15.htm
3. GitHub. (2018, July 27). User Search. Retrieved from https://github.com/search?q=type:user&type=Users
4. Firestine, B. (2017, April 10). Celebrating nine years of GitHub with an anniversary sale. Retrieved from https://blog.github.com/2017-04-10-celebrating-nine-years-of-github-with-an-anniversary-sale/
5. Gousios, G., Vasilescu, B., Serebrenik, A., & Zaidman, A. (2018). Lean GHTorrent: GitHub Data on Demand. Retrieved from https://bvasiles.github.io/papers/lean-ghtorrent.pdf
6. Frederickson, B. (2018, January 25). Ranking Programming Languages by GitHub Users. Retrieved from https://www.benfrederickson.com/ranking-programming-languages-by-github-users/
7. Mashable. (2018, March 17). It pays to learn to code with C# and here’s why. Retrieved from https://mashable.com/2018/03/17/coding-course-class-bootcamp/