Can you create a practice site without having a domain?

I’m interested in using SquareSpace to build a couple of websites but I’m wondering if I can build a site BEFORE I have a domain name to associated with it? 
 

In one case, I have a website that I built with a coding buddy 16 years ago (using PHP) that’s now obsolete and on its last legs. I did the design and content but am clueless about coding; or else I wouldn’t need SquareSpace. However, I can NOT migrate it/swap it to a SS site until I have a complete and functioning website here on SS. The business it’s for depends on the site being up constantly. In the other case, I have a new company forming and the naming/incorporation isn’t complete yet so acquiring a domain name isn’t possible. I’d like to start the work of creating a website for it, though, so that I won’t have much to do once we have the domain secured. 
 

IF this is possible, which I’m hoping it is, how to I go about building them sans the domain name? Is this an option that you’re provided as you start with SS? I’m totally new here so I joined the forum to get help and advice on this and all the questions I’m sure will arise once I start trying to build the sites. 
 

Thank you to anyone who replies!

- Tengu_Pirate

You can build with random built-in domain, something like this: yoursite.squarespace.com, for free.

When you complete the site, you can connect the domain name, or you can also use the built-in domain.