Before HTML5 application data was stored in what?

Answer 1

Yassine Lassoued APIs have been around a long time but before hypertext markup language we were using what was known as standard generalized markup language or sgml / document type definition and often built around DOS floppy systems. Later internet and APIs allowed SGML to cross to xml ( extensionable markup language )

To read more about SGML, xml, html and xhtml reference

https://www.britannica.com/technology/computer-programming-language/SGML
and
https://www.w3.org/TR/WD-html40-970708/intro/sgmltut.html#h-2.3.1

Answer 2

Yassine Lassoued
I put your question into the Q&A search bar and got 20 hits directly relating to this query.

Why don't you research this for yourself

Answer 3

I believe the Local Storage and Session Storage APIs were supported years before the HTML5 spec was officially approved and released in 2014.

So... technically, Local Storage and Session Storage APIs existed before HTML5. 😉

That said, prior to these HTML5 features, the only mechanisms for persisted state were via server side sessions, cookies, and possibly page to page form data.

CREDIT: David Carroll