They are in general five in number:
1- Any form of human speech whether haqiqi or hukmi
3- Excessive movement without it being to rectify
4- Leaving out any of the obligatory (fard) elements without an excuse, even if it occurs without his choice
5- To deliberately invalidate ones wudu
 What is meant by human speech is that which is can be asked from another human being, and that one asks Allah (the most high) for this in the form of a supplication (dua) such as saying “O Lord give me 100 dinars” this is what is called kalam al-hukmi, i.e. It maybe in the form of a dua to Allah (the most high) but it is something which can be asked from another human being and is therefore regarded as human speech. An example of something which cannot be asked from another human being is supplicating: ‘O lord forgive me my sins’, this does not invalidate the prayer as another human being cannot be asked to forgive your sins. Al-Jawhar
 The definition of laughter is that it be audible to the person praying and not the person praying next to him, this invalidates the prayer but not the wudu.
Smiling invalidates neither the prayer nor wudu.
Loud laughter is that which is audible to the one praying and those around him, it invalidates both the prayer and the wudu, however with the condition that it be from an adult who is awake in a prayer consisting of bowing and prostrating. It is the same if the loud laughter was deliberate or accidental. Sharh al-Wiqayah (p.90) Tabyin al-Haqaiq (1/11) Fath Bab al-Inayah (1/68) al-Ikhtiyar (1/18)
 What is meant by rectifying is walking to make wudu if ones wudu is invalidated during prayer, or to kill a snake etc. The definition of excessive movement is that which the one looking at the person praying would think that they were not praying. This view has been adopted by the generality of the scholars and was chosen as being the strongest view by al-Haskafi in al-Dur al-Muntaqa (1/120), al-Sarkhasi in al-Mabsut (1/191) al-Kasani in al-Badai (1/241). This was also the position of the author of al-Tabyin, the author of al-Muhit and Sadr al-Shahid. See the al-Shurunbulali’s notes to al-Durar (1/104)
 Such as leaving one of the obligatory (fard) elements of the prayer without reason, such as an ill person not standing due to being unable to do so. Likewise an illiterate person not reciting the Quran within the prayer, the prayer is not invalidated due to his having a valid reason. However the prayer is invalidated if it occurs suddenly without intending the missing of an obligatory act, an example being: a person is praying and some filth stains the clothing and cannot be removed immediately. Al-Jawhar
 This is before sitting for the length of the tasahhud, and is by deliberately passing wind or urinating. As for after having sat for the length of the tashahhud it is defined as exiting the prayer with ones own action and does not invalidate but rather the prayer is completed. However exiting the prayer with the salam has been left out which is wajib, therefore if the one praying has invalidated their wudu, they go to perform wudu and return back to build upon their prayer, the scholars have however set down ten conditions for this, details of which can be found in Dur al-Mukhtar and Rad al-Muhtar (1/403), Sharh al-Wiqayah (p.158-159) and Tabyin al-Haqaiq (1/145-146).