Your Adobe ID is a unique identifier which syncs across all Adobe Creative Cloud platforms. This way, you can use the same username and password for all of your Creative Cloud needs including Photoshop, Behance, and now Portfolio.
Not only does this relieve the need to remember multiple email addresses, passwords, etc., but all of your information syncs across the cloud. This allows creatives to upload work directly from one creative platform to another, saving time and streamlining the creative process.
To create your own Adobe ID visit https://accounts.adobe.com/