what type of storage does a computer use when a user enters data into an online form and before they submit the form?

The data is held in the computer’s main memory (RAM) while you’re typing it into an online form and before you press Submit.

Quick Scoop

When you click into a text box and start typing, the browser keeps those characters in RAM as part of the current page’s state. Only after you submit (or if the site uses extra scripts to auto-save) does that data get copied somewhere more permanent, like a server database, localStorage, or cookies.

Think of it like this

• While you type:
  • Your keystrokes update variables in the browser running in RAM.
  • Nothing is necessarily written to disk or sent over the network yet.

• After you submit:
  • The browser sends the data over the internet to the server.
  • The server can then save it in a database or other permanent storage.

Until you hit “Submit” (or a site explicitly auto-saves), your form entries live only in volatile RAM , tied to that open page in your browser.

TL;DR:
Before submission, the computer uses temporary main memory (RAM) to store what you typed into the online form.