The most current type of media in household networks is Cat 6 Ethernet cable connected to devices using RJ45 connectors. Also known as 8P8C (eight position, eight contact), the connector ends of the Ethernet cable look like a phone jack connector, only larger and with eight wires instead of four. This is important to remember when making a selection because fiber optic network interface cards are available at a much more reasonable price. While the fiber NIC devices have come down in price, typically routers and other networking components that are fiber-based are still on the higher side of the price spectrum.
In terms of the RJ45-equipped devices, most only come with one available port. But there are those that can host up to four ports on one NIC. These are typically for business environments, but can be extremely helpful for busy and very powerful home media servers using a technology called network bonding. Essentially, this allows data to be transmitted over more than one cable to allow for a higher throughput and less latency for file access. If you're connected to multiple network devices, they can also provide fault tolerance in the event of device failure. Typically, unless the server is being accessed by more than three devices at a time on a regular basis, network bonding should not be required.
Two major interfaces are available to desktop PCs, depending upon the motherboard’s interface. Unfortunately, they have similar names, so the nomenclature can be confusing if you are not familiar with them. The older standard, PCI, carries a double-sided 62-pin zero insertion force (ZIF) socket. This standard is still being produced and developed on most motherboards, but not all. The newer standard is PCI Express, shortened to PCIe. You'll find PCIe slots in x1, x4, x8 and x16 configurations. Most add-in NICs drops into a single-lane slot with 18 pins. It is important not to confuse PCIe x16 and PCI slots; PCIe x16 is slightly longer and often has a card snap towards the end of the slot.