Juncture business card marking system by Rich Gerrish

"Juncture is a fantastic idea. Simple, practical and really worth knowing." -  Marc Paul
"It’s a genuinely great system for marking your business cards. I would go so far as saying it’s an essential tool for all mentalists to learn!" - Looch

"The best ideas in mentalism (and life in general I guess) are the simplest ones. This one is up there with the best. Great thinking." - Stephen Young

"I've spent an indecent amount of time trying to come up with invisible markings for use with double blank cards but to no avail, so when Rich showed me this I just thought of course, it's obvious and so innocent, why didn't I think of that. This is definitely something I'll be using." - Scott Creasey

Juncture is a visual marking system for business cards, blank cards or envelopes. The basic system allows you to uniquely identify up to 13 cards. As soon as you see what has been drawn or written on the card, you know who the card belongs to. Additional ideas from  Iain Dunford and Greg Arce increases the number of identifiable cards to 52!
You can use any pen, including a borrowed pen.
You can use any cards, including borrowed cards.
Nothing extra is needed, the markings are hidden in plain sight.
Applications include:
Liar / Truth teller
Pseudo psychometry
Sneak Thief / Desire (routine not taught)
Q and A (routine not taught)
And many more ...