There are hundreds of programming languages out there: some exploded in popularity and then diminished, some started as niche languages and never expanded beyond a core group of devotees, but one, in particular, has withstood the test of time. So why is Python, designed in 1989 and first released in 1991, still relevant today?
You Can't Be Everything to Everybody... but it Helps
Python developers value its flexibility. Python's creator, Guido van Rossum, had previously worked on the (significantly less popular) ABC programming language and built Python with the pieces of ABC he liked and scrapped the parts he didn't like. Some popular carry-overs and additions in Python include lists, dictionaries, basic statements, and indentation.
Guido van Rossum also used lowercase rather than uppercase keywords, and he made Python with a small core that is easy to extend, rather than monolithic in design like ABC. This extensibility helped to initially separate Python from the pack, and today it's known as a versatile general-purpose language.
Have Your Servers and Your Front-End Too
Mirroring the flexibility in language features above, Python has broad appeal across programming disciplines. As a multi-paradigm programming language which can conform to many different design patterns, Python mixes simple syntax, text processing, and scripting abilities that appeal to IT and DevOps engineers with an architectural flexibility that can accommodate more advanced architectures that appeal to application programmers. Additional extensions have brought loyalty from other groups; web developers value its web frameworks (Django, Pyramids) and researchers value Python's ability to handle scientific computing libs (NumPy, SciPy).
Python is one of the most popular languages measured on GitHub and has a huge amount of support as a popular in-house language at Google. Other companies (such as Facebook and Instagram) use Python internally, and still more create Python SDKs to give developers coding in Python easier access to their APIs. There can be broad support for Python across all types of engineers in each of these companies. Python is approachable enough that educators use it as an introductory programming language, and experienced developers use it to build side projects for fun. This broad support and appeal is a testament to Python's continued relevance.
"Now, it's my belief that Python is a lot easier than to teach to students programming and teach them C or C++ or Java at the same time because all the details of the languages are so much harder. Other scripting languages really don't work very well there either." -Guido van Rossum