Hyde here from Shopify.
Dropshipping is a retail fulfillment method where a store doesn't keep the products it sells in stock. Instead, when a store sells a product, it purchases the item from a third party and has it shipped directly to the customer. This is perfectly legal and is actually how a lot of businesses operate in this day and age.
Our ultimate guide to dropshipping may help clarify how it all works, and will walk you through everything you need to know about starting off, finding suppliers and maintaining your business. Check out our Dropshipping 101 course on our Academy, as well as our Intro to Dropshipping.
I hope that helps!
All the best, Hyde.
With absolute certainty, I can tell you that Dropshipping is perfectly legal.
To learn more about How Dropshipping Work, check out: How Dropshipping Works: A Complete Guide
To learn more about profitable products and niche to dropship, check out: 40+ Dropshipping Niches and Products To Sell
Let me know if my answer is of any help, cheers