A rechargeable flashlight is a portable illuminating device that has a built-in way of putting back the juice in the rechargeable batteries inside it. It will have a port where a charger can be attached or some even have terminals to plug into AC outlets. Whatever means the flashlight uses, if the batteries do not need to be taken out of the flashlight to be recharged, it can be considered a rechargeable flashlight.
When looking for a rechargeable flashlight you have to consider a few things and choosing one that best suits your needs or lifestyle. One that is best suited for boat use may not be necessarily the best for the homebody or for an everyday carry. Think about the charging options, does it use a USB cable, car adapter, etc. One thing that may be of great importance is safety and one should be eyeing the ones that offer protection against overcharging and discharging, discharging, because sometimes batteries can get damaged from getting drained too fast or too much.
Batteries used for the rechargeable flashlight might also be a consideration because they use different kinds and availability may be important to you and runtime may also be something you also want. Not having a flashlight is bad and having one that works is better than nothing but a good flashlight can certainly make a big difference, having one that is a rechargeable is icing on the cake.