Java: Originally invented in 1991 as a programming language for smart televisions, Oracle's Java is now the most popular language in the world — a position solidified by the fact that Java is crucial to Android app development and lots of business software.
PHP: This language for programming web sites is incredibly common — some estimates say it powers one-third of the web. Big sites like WordPress, Facebook, and Yahoo use it. A lot of programmers also hate PHP with a passion — Stack Exchange founder Jeff Atwood once wrote "PHP isn't so much a language as a random collection of arbitrary stuff, a virtual explosion at the keyword and function factory."
Perl: Originally developed by a NASA engineer in the late eighties, Perl excels at processing text, and developers like it because it's powerful and flexible. It was once famously described as "the duct tape of the web," because it's really great at holding websites together, but it's also not the most elegant language.
C: One of the oldest programming languages still in common use, C was created in the early 1970s. In 1978, the language's legendary and still widely read manual, the 800 page "The C Programming Language," saw print for the first time.
Objective-C: The original C programming language was so influential that it inspired a lot of similarly-named successors, all of which took their inspiration from the original but added features from other languages. Objective-C has grown in popularity as the standard language to build iPhone apps, though Apple's been pushing its own Swift language, too.
Visual Basic: Microsoft's Visual Basic (and its successor, Visual Basic .NET) tries to make programming easier with a graphical element that lets you change portions of a program by dragging and dropping. It's old, and some think it's lacking features next to other languages, but with Microsoft's backing, it's still got its users out there.
Ruby: Like Python, developers like this 24-year-old language because it's easy to read and write the code. Also popular is Rails, an add-on framework for Ruby that makes it really easy to use it to build web apps. The language's official motto is "A programmer's best friend."
Python: This language traces back to 1989, and is loved by its fans for its highly readable code. Many programmers suggest it's the easiest language to get started with.
R: This is the programming language of choice for statisticians and anybody doing data analysis. Google has gone on record as a big fan of R, for the power it gives to its mathematicians.
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