There is a huge variance between normal USB ports rated at 500mA and dedicated charging ports which range all the way up to 3,000mA. This leads to a rather important question: If you take a smartphone which came with a 900mA wall charger, and plug it into a 2,100mA iPad charger, as an example, will it blow up?
In short, no: You can plug any USB device into any USB cable and into any USB port, and nothing will blow up — and in fact, using a more powerful charger should speed up battery charging.
The longer answer is that the age of your device plays an important role, dictating both how fast it can be charged, and whether it can be charged using a wall charger at all
If you have a modern USB device — really, almost any smartphone, tablet, or camera — you should be able to plug into a high-amperage USB port and enjoy faster charging. If you have an older device, it might only work with original (500mA) USB 1.0 and 2.0 PC ports.
There are a few other things to be aware of. PCs can have two kinds of USB port — standard downstream or charging downstream. As a result, you might have a device that charges from one port on your laptop, but not from the other. This is a trait of older computers, as there doesn’t seem to be a reason why standard downstream ports would be used, when high-amperage charging ports are available.