What Chrisjcks said.
But don't confuse boost charging with bump charging.
Boost is simply charging when you get a chance.
Bump is tricking the charge controller into over charging the battery in the hopes of getting a few more minutes out of the phone. It is harmful to the battery.
Bump charging is charging to full, take it off the charger, wait maybe a minute, then pop it back on the charger. It works with some devices by tricking the charger into overcharging beyond what the manufacturer specified as the max charge.
Boost is good, bump is bad.
Boost is actually the best way to manage your battery, after draining it completely ONCE when new to calibrate the charge controller.
This is where the Battery Swappers have it all wrong. They run their phone till its almost dead then swap in a new battery. Their charge controllers are always confused, and their dead batteries sit in their pocket till they get around to charging them. Bad for the battery in both ways. Then they put the phone on the charger and charge both of them to full. Worse, they buy an external charger that is not matched to the battery, and actually damages the battery.
An external battery makes so much more sense. You can boost charge any time you have a few minutes, (don't try to convince anyone you are on the phone for 8 hours straight), even when its in your pocket.