This could be the last major update for the HTC One (M8), which was launched with Android 4.4 pre-installed back in March, 2014. Since then, the phone has been updated to Android 4.4.3 and Android 5.0, Android 6.0 brings with it Doze, which extends the battery life of the phone by putting it in a deep sleep state when it is not being used. Google Now on Tap will show search results based on the content appearing on the screen at the time the search request is made, and a change to app permissions allows them to be granted or denied on a feature-by-feature basis.
Before starting the updating process, HTC One (M8) owners on T-Mobile should make sure that they have hooked up with a Wi-Fi network. Additionally, the battery on the device should be charged to at least 50%.
source: @moversi via TmoNews