How do online services (Netflix and other online services that have a subscription) know what card company you have just by 1 or 2 numbers?

[gta_fan]

I've always wondered this when I put in my card info

[Anonymous]

Yes, actually. So credit card companies all start with a different number. Like Visa always starts with the number 4, MasterCards start with 5 and Discover starts with 6. Or at least this is what I've been told/taught. I worked with telemarketing for quite some time and as soon as you typed in the first number of the credit card, it always popped up with the company immediately. American Express cards have more numbers than other credit cards too I think.

[jshm2]

Luhn Algorithm

https://en.wikipedia.org/wiki/Luhn_algorithm

It's a simple calculation from which they can fid and identify cards and their respective banks.

[Anonymous]

Different card companies have different initial numbers or it's saved in your browser? Apple Pay