A vCard QR code carries a small contact file (vCard 3.0, the version every phone reads). When someone scans it, the phone offers "Add contact" with the fields already filled in. It is the format that works without an app, a server, or a profile page in the middle.
The code holds the data itself, so it is larger than a link code: a full card with address and note can run to 300 characters and a dense grid. Keep what matters (name, mobile, email, company) and the code stays comfortable at business-card size. The scan check on the right tells you if you have overloaded it.
On a business card the code should be at least 2 cm wide with a clear margin around it. Export SVG and give it to whoever lays out the card, or PNG at 1024 px for an email signature.
Questions
What is the difference between a vCard QR code and a link to a profile page?
A vCard code works offline and forever: the contact details are inside the code. A profile-page code depends on a website staying online. Many "digital business card" services use the second kind, and the code dies when the subscription does.
Can I include a photo in the vCard?
Not in the code itself. A photo makes the data far too big for a scannable grid. You can, however, put your picture inside the code visually with the Picture tab.
Why is my vCard code so dense?
Every character adds dots. Addresses and notes are the usual culprits. Drop the optional fields and the grid shrinks.