With the introduction of the new 'TouchBar' line of Macbook laptops, Apple have once again made things a little difficult for those of us who want to run better quality monitors.
The only port these fancy new machines have available now is USB-C, AKA USB 3.1, (or sometimes Thunderbolt 3), which creates complications as, to date, most monitors do not currently offer this connection. Whilst in principle this can offer a very tidy approach - where one cable from the monitor acts as both video input AND charger for the laptop, meaning you can create a near cable free experience on your desk....this same convenience means the USB-C port is considerably more difficult to implement & support than a normal video input on a monitor like a DisplayPort - because of the powered port requirements. This difficulty effects the cost to the monitor maker, and may mean that they need to raise monitor prices, something monitor makers are of course loathe to do.
It remains to be seen, in early 2017, whether or not monitor makers will begin to offer this connection as a standard thing. Most currently don't, so odds are that if you are one of the many sensible folks who want a more colour accurate screen than Apple can provide, you'll need to work out how to attach your external screen choice to your Macbook.
It's not really hard, but so far the adaptors are in short supply and there are potential compatibility issues.
(Obviously, if you have a dedicated video output available in addition your USB-C port, such as HDMI, then you should use that!).
The trick is to buy the adaptor for the best connection type you have available on your screen. Now might be a good time to review our article on Monitor Connections in general:
Essentially, you want to attempt to hook up your screen in this order - from best to worst - that is, choose from this list the top most entry that your monitor offers (and most modern monitors have at least one of DisplayPort or HDMI):
The best option, if your screen has it, is DisplayPort - it has the best, most robust connector in physical terms, and also is the most likely to offer things like 10 bit input support - so if you have a DisplayPort input on your monitor, use that by preference. Otherwise, use the HDMI input.
If your monitor has neither of those options, then it is an older/more basic model. The next best one to use is DVI, which is at least still a digital connection.
You would only resort to using VGA under exceptional circumstances at this point - as an analogue connector it's effectively obsolete at this point.
Once you've chosen the type of connection you're going to use (ideally USB-C to DisplayPort) - you need to get an appropriate adaptor/cable.
The key things to look for (and make sure when you search you use both the USB-C and USB 3.1 terms, as both are commonly used, often on the same site!)
Please note we are not endorsing any particular products or suppliers below (just reporting our own experience/feedback we've heard) - and we can offer no guarantees on particular products working for your needs - please research thoroughly and talk to the these suppliers directly if you have any questions about their products.
For an online supplier, we tend to recommend CableChick (yes they're awfully branded, but they offer good value/service). This link will search their site for USB 3.1 products.
Mac Fix It seem to have a bunch of options lately, including hubs.