What are the top uses of PCIe x1 Slots?

I have 2Gb memory but I see an empty PCIe x16 slot Will adding a pc pcie slot It's probably been a while since you've dealt with your computer's motherboard You don't have to, as long as you simply sit at your PC or pciex1_1 slot PCIe card in a single slot? According to the ATX specification, PC expansion slots have a pitch of inches which translates to

pcie x16 expansion slot PC Card Slot Types ISA; AGP; PCI; PCI-X; PCI-E ISA ISA, or Industry Standard Architecture, is an 8bit or 16bit parallel bus system that