A language that has so many purposes, yet gets pushed to the wayside regularly in our industry, is XML. Being more flexible than HTML in syntax, it’s almost like a Swiss Army knife in its unique and multi-functional purpose. Used in so many aspects of the web — from software UI settings, non-SQL local databases, public APIs of third-party services like Twitter’s, Sitemaps, and syndication formats like RSS — it’s become a mainstay of web development.
Oddly enough, while XML is so durable, it’s not generally considered a core requirement to know. However, remember that with the web constantly evolving, the need for XML is only likely to increase to cope with our diversifying data needs.
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