Things which invalidate prayer

1. Urine, feces, and passing gas
2. Laughing loudly. How ever only smiling does not invalidate one s prayer.
3. Turning away from Qibla during prayer
4. Speaking
5. Sleeping
6. Sighing or moaning from pain

Adopted from the book: "Kashaful Salat" by: "Seyyed Baqir Nisar Zaidi"