Consider what ports are installed on Apple's laptops (MacBook Pro, MacBook Air).
MagSafe 2 port
MagSafe 2 - a port for connecting the power source has some structural features, such as a compound for magnet that allows easy disconnection of the power cord. This prevents the port and the power cable from damage in the event of physical impact.
Thunderbolt 2 port
Thunderbolt 2 - Universal digital port designed Applei Intel, like HDMI and DisplayPort. It has some advantages in data rate 20GB, combines PCI Express (PCIe) and DisplayPort (DP) in the same cable interfaces, can be connected in series to 6 digital devices. Used mainly in laptops and Apple monitors. Due to the high cost is not installed in the devices of other manufacturers. As planned by the developers (Intel and Apple), this connector should displace HDMI and DisplayPort but manufacturers prefer cheaper counterparts. Yes, and the transmission rate of HDMI and DisplayPort ports increased than provide support for content transfer UHD resolution. Therefore, this interface is still alive purely through the efforts of Apple.
USB 3 port
USB 3 - standard universal port for connecting eg a computer mouse, phone and other devices.
SDXC card slot
SDXC card slot - a slot for an SD memory card, SDHC, SDXC, as well as their reduced standards across the adapters. Familiar user port.
HDMI - digital output port for video streaming, while Apple is betting on these ports Thunderbolt but not in televisions and monitors from other manufacturers if the user will not be able to connect your laptop to your TV sales of Apple technology can be reduced, which is not very good.
Apple minimize the number of ports leaving only the most necessary and most used.