This seems to jump into web-based APIs without mentioning it. An API does not have to be web based: it could be a set of classes, or methods, or modules or func

This seems to jump into web-based APIs without mentioning it. An API does not have to be web based: it could be a set of classes, or methods, or modules or functions to be used from a language directly. Web services, of course, tend to have web-based APIs. But that's a subset of all APIs. Since this article seems aimed at beginners, I think it's an important distinction to note. You would not want beginners to think that APIs are always web-based because then they'll be confused by things like WebGL, which is also an API but does not involve web requests or AJAX.