What power adapter do I use?

Hi, I want to power my arduino using the USB connection.
Wich adapter do I use for it?

Ive read something about 7 to 12V DC for the 5.5mm pin
Does this also count for the USB connection?

The USB connector is a standard 5 volt 500 mA connection world wide for USB 2.0
You can look up USB power standards in google.

For the power jack you are actually better in the 7 to 10 volt range taher than 12 volt as it is safer for the board long term.

Depending on what else you have connected to the board some external components may require thier own power supply to meet current consumption needs as the Arduino boards are limited in that respect.

Thank you! You really helped me out!