Diachronic study focuses on change which has taken place over the whole duration of a language's existence.
Synchronic study focuses on change which is taking place currently.
Diachronic study has to employ a variety of techniques, because for most of the period of study, sound records do not exist. One example of a current phonological change is the recent rise in intonation at the end of utterances in English. This is particularly prevalent among teenagers. A descriptive attitude is one which accepts the inevitability of change in language. It concentrates on describing the way in which language is evolving like any other living phenomenon.