This is an old revision of the document!
The bootloader is the code that is pre-programmed on your Digispark and allows it to act as a USB device so that it can be programmed by the Arduino IDE.
The Digispark runs the “micronucleus tiny85” bootloader version 1.02, an open source project: https://github.com/micronucleus/micronucleus originally written by Bluebie: https://github.com/Bluebie.
CAUTION We are not at this point supporting upgrading the firmware, so if you decide to, you do so entirely at your own risk.
The Digispark uses the Arduino IDE 1.6.5+
http://digistump.com/package_digistump_index.json
and click OK