When we talk about lettering we're talking about drawing custom letters for a specific project rather than using an existing typeface. The term lettering is used in design a lot, especially in the last few years, when this way of handling type has become very popular. In my opinion it is actually overused lately. It has become the cool thing to do, rather than the thing to do when it's right for the project.
But there is definitely more good than bad that has come out of this lettering explosion. Luckily for our eyes (and for brands out there), more talented and dedicated designers have come to love this art. They put their hearts and souls into their work, giving us lots and lots of high quality eye candy. Lettering isn't in the very least an easy task, it is very involved and time consuming.
Here are a couple of great examples I quickly grabbed from the web:
If you enjoy looking at beautiful custom type, now is the time! But since trends come and go, I think using existing typefaces might just become the cool thing to do pretty soon. Not that lettering will ever stop being an important part of branding and design – it has always been and it will always be.