With the release of the "late 2016 MacBook Pro" models Apple has drastically changed the amount and type of ports of the MacBook Pros. Except for the headphone jack the new models offer only Thunderbolt 3 ports. You can find more details about thunderbolt 3 here (http://www.apple.com/thunderbolt/) and here (https://en.wikipedia.org/wiki/Thunderbolt_(interface)#Thunderbolt_3).
Thunderbolt 3 offers high throughput and allows to daisy-chain devices.
Since it requires extra adapters to connect almost all of todays existing accessories (mouse, ethernet cable, monitors, external disks with USB3 or FireWire,...) we have decided to continue to make a MacBook Pro with the "classic connectivity" available in the CERN PC shop. Below you can find details of the ports offered by the new Thunderbolt 3 models and the models that offer the "classic connectivity", better suited in case you have several accessories that require the old connectivity.
MagSafe adapter for charging
USB 3 port(s)
Thunderbold 2 port(s)
SDXC card slot
3.5mm headphone jack
Thunderbolt 3 Connectivity
1, 2 or 4 Thunderbolt 3 connectors (http://www.apple.com/thunderbolt/) with varying speed
Used for charging, networking, connecting accessories
Needs adapters or special cables for most of the existing accessories
Confusion about compatible hardware
1 3.5mm headphone jack
To connect existing devices you will probably need specific cables and / or adapters.
A USB-C to USB adapter will be needed to connect USB devices like mice, keyboards, external USB disks, USB sticks, iPhones, ...
A USB-C to Gigabit Ethernet adapter will be needed to connect to a wired network.
A USB-C to VGA adapter will be needed to connect to VGA screens or beamers.
A USB-C to HDMI adapter will be needed to connect to a HDMI screen.
A USB-C to Display Port cable will be needed to connect a monitor with Display Port.
A USB-C to thunderbold2 connector will be needed to connect to a thunderbold display.
To connect a firewire device you would need a USB-C to firewire adapter - which don't exist as far as we know. You could get away with using a firewire to thunderbold 2 cable and the thunderbold 3 to USB-C adapter. Or you are lucky and your firewire device also has a USB connector, in which case you get away with a USB-C to USB adapter.
Some information is available from https://support.apple.com/en-us/HT201736.