I stumbled upon this 'list of programming' languages and found that popular languages like Python are not standardized? Why is that, and what does 'Standardized' mean anyway?
"Standardized" means that the language has a formal, approved standard, generally written by ISO or ANSI or ECMA. Many modern open-source languages, like Python, Perl, are not formally standardized by an external body, and instead have a de-facto standard: whatever the original working implementation does.
The benefits of standardizing a language are a) you know the language won't randomly change on you, b) if you want to write your own compiler/interpreter for the language, you have a very clear document that tells you what behavior everything should do, rather than having to test that behavior yourself in the original implementation. Because of this, standardized languages change slowly, and often have multiple major implementations.
A language doesn't really have to be standardized to be useful. Most nonstandard languages won't just make random backwards-incompatable changes for no reason (and if they do, they take ten years to decide how to *cough*Perl6*cough*), and nonstandard languages can add cool new experimental features much faster (and more portably) than standardized languages.
A few standardized languages:
Non-standardized languages:
A full list is on Wikipedia.