The Ordinals protocol is a system for numbering satoshis, giving each satoshi a serial number and tracking them across transactions. Simply put, ordinals allows users to make individual satoshis unique by attaching extra data to them. This process is known as “inscription”.
You can inscribe many forms of data to the Satoshi like MP3, PNG and HTML files like this one. You are however limited to the 4MB block size.
As ordinals are new the market places to buy your ordinals are still in its infancy. For now below are a list of some of the Ordinal market places I have used.
This site was made completely built on Bitcoin blockchain with Ordinals and Btc Domains