FARZ (COMPULSORY)

Farz is a positive command which is established by absolute proof (Daleel Qatai). For example salah, zakaat, fasting, hajj etc.
One who believes in it but neglects it without a Shari excuse (excuses which Islaam accepts, not self made excuses) is termed as Faasiq (Great Sinner) and deserves severe punishment.

One who altogether denies it for example it is not obligatory to pray salah or do hajj; he becomes a Kaafir (disbeliever) and will remain in Hell forever inspite of carrying out other Islamic commands unless he repents and embraces Islaam again.
 

THERE ARE TWO TYPES OF FARZ:

1. Farz Ain
Means it is obligatory on every individual to execute it for example salah, zakaat etc.

2. Farz Kifaayah
Means if a group of muslims carry it out others are discharged of it but if no one carries it out then all will be termed as faasiq and earn the displeasure and punishment of Allah for example salat-ul-janaza (funeral prayer). If few Muslims offer it then others are discharged of sin.
 

WAJIB (ESSENTIAL)

Wajib is a positive command, the proof of which is established from Daleel Zanni (non-absolute) which is lower category than Daleel Qatai which elevates the command of Farz. One who rejects or neglects it is a faasiq (sinner) and deserves punishment.

SUNNAT

Literally means path or way. In Sharia it refers to speech, action and silent approval of Prophet Muhammad (may Allah's peace be upon him). The term Sunnah is also used for action of the companions especially the four rightly guided caliphs (may Allah be pleased with them).

SUNNAT IS OF THREE TYPES:

1. Sunnate Mukada (Emphatic Sunnah)
Is an action which was continuously practiced by Prophet (may Allah's peace and blessings be upon him) and was not abandoned without a valid reason. If a person neglects it continuously then it is sinful for example, azaan, sunnat rakat of Fajar, Zohar, Maghrib and the two rakats after Isha Salah. To offer Salat-ul-Tarawih is also Sunnate Mukada.

2. Sunnate Ghair Mukada (Non-Emphatic Sunnah)
Is an act of which was practiced by the Messenger of Allah (may Allah's peace and blessings be upon him) and his companions but sometimes they abandoned it without an excuse. To constantly neglect it is not desirable in Sharia. Such as four units of sunnah before Asar and Isha salah.

3. Sunnate Mukada Kifaayah
Is an act if few people carry it out then others are discharged from it, for example Itikaf in the last ten days of Ramadaan, offering Tarawih prayer with jamat but Tarawih prayer itself is Sunnate Mukadah.

MUSTAHAB (DESIRABLE)

practiced it occasionally. If one carries it out then there is a great reward but there is no sin if one does not practice it. It is also known as Mandoob (Recommended), Tatawu (Voluntary) or Nafl (Supererogatory).