What is the purpose of express card slot in my laptop?

I have a Dell Precision M4500 and I read on the manufacturer's website that it has an ExpressCard 34 slot How to get ExpressCard 34

The wide slot features a novel guidance mechanism that steers ExpressCard34 modules into the connector socket The ExpressCard Standard also allows extended

legend of perseus slot The PCAN-miniPCIe card enables the connection of embedded PCs and laptops with PCI Express Mini slot रo 44, Ex Tax:रo 37,

magic slot gta 5 ExpressCard34 slot Compatible OSX : *Lion 5 or later, Monterey to Sonoma !!