Who doesn’t love Arduino boards and their various derivations? Getting started with them is a great introduction to electronics and programming, and the ecosystem extends to much more advanced projects as you progress in your hobby and/or profession. On the other hand, one barrier you’re likely to bump into sooner than later is that these and most other boards of this kind need to be plugged in.
One solution is to get a USB battery — like the popular “lipstick” chargers — and plug it into the board’s USB connector. That, however, is more of a temporary solution, and takes up the USB port which you may want to use. There is also a power plug on many of these boards that could be adapted to portable use. And if you’re willing to get out your soldering iron, just about anything is possible.
Or, for something refined and easy, Tindie seller Iohippo designed the ArduBoost Lipo. This add-on allows you to hook up and charge a LiPo battery on several types of Arduino boards, such as the Uno and Leonardo. Power is provided via a TPS61026 boost converter, which can provide up to 1A of current at 5V. Importantly, the ArduBoost features a set of screws that secure it to the dev board, leading to its refined and semi-permanent look!