Browsers primarily run the JavaScript programming language, while back-end developers must pick from a dizzying number of programming languages and related tools.

Programming languages: Python rules while Java dips Tiobe also predicts that Julia, a programming language with roots in MIT, will become a top 20 language in 2021.

Tiobe index of programming language popularity identified Python and C++ as the languages with the greatest increases in popularity in 2020.

JavaScript, CSS, HTML, HTML5, MySQL, WordPress, PHP and Python are the most in-demand tech skills from employers in 2020, according to a Upwork report.