Many years ago I met the CEO of a tech company at a networking event for recent college grads that they hosted. Like a job fair but with a twist. Having read Brian D. Krueger's excellent "College Grad Job Hunter" , I had business cards prepared. This was long before Moo.com so they were printed out on my Deskjet on Avery pre-perforated card stock. I went with my ill-fitting suit and mismatched shoes/belt, and I was talking to someone from a small tech company and I got a tap on the shoulder, "Our CEO would like to get a picture with you." Having miniscule networking mojo and knowledge, I actually followed the PR person without excusing myself. We took the photo, and I asked if I could give him my business card. He said yes, and he gave me his.
The next day, I wrote him a letter. I honestly wrote how I liked that this networking event was not the usual deal but more like a classy cocktail event and a great opportunity to meet other companies in a less-networky, relaxed atmosphere. I thanked him and the company for hosting it.
I ended up later getting hired by his company (I was invited to apply, someone called me) and worked there for many years, as I learned the art and trade of software development, starting from nothing and someone who managed to bluff their way through the interviews.
 https://www.amazon.com/College-Grad-Job-Hunter-Entry-level/d... (highly recommend this, written from the perspective of the hiring manager)