There are four tones in Mandarin that must be followed for proper pronunciation.
1. first tone ( ā )
flat, high pitch - more sung instead of spoken
2. second tone ( á ) low to middle, rising - pronounced like the end of a question phrase (Whát?)
3. third tone ( ǎ ) middle to low to high, dipping - if at the end of a sentence or before a pause, it is then followed by a rising pitch
4. fourth tone ( à ) high to low, falling - Pronounced like a command (Stop!)
5. There is also a fifth tone, the neutral tone, which is used rarely, mostly for phrase particles.