بسم الله الرحمن الرحيم
In the Name of Allah The most Gracious The Most Merciful
There are 8 nullifiers to the prayer:
1. Speaking during the prayer. One has to be aware they are in prayer and knows what they are doing and does it on purpose. If someone speaks from ignorance or out of forgetfulness then the prayer is still valid.
5. Part of ones ‘awrah showing
6. Turning a great deal from the direction of the Qiblah
7. Moving too much and for no valid reason
8. Losing ones purity