Batteries

Powering your drivetrain for an autonomous robot likely means batteries (although BEAM robots use solar cells and capacitors for collecting and delivering short bursts of power).

For your motors, you're probably going to use a holder of AA or AAA batteries, either disposable alkaline or nickel-metal hydride (NiMH) rechargeable. There are also battery packs, frequently lithium-ion polymer (LiPo), used in R/C vehicles. These are all dry-cell type batteries.

There are also sealed lead-acid (SLA) batteries commonly used in more power-hungry robots (such as larger bots and high-power combat robots). It may sound like a joke, but to educate yourself on batteries, get thee to Battery University. It's an online repository of pretty much everything you always wanted to know about batteries but were afraid to ask.