In the Muslim world, marriage customs and traditions vary very much. However, they all retain the Islamic obligatory acts, which make the marriage contract valid.

All Muslims marriage contracts must include the following:

1. The bride and the groom must enter into the nikah (marriage) contract by consenting to the marriage.

2. The woman must have a wali amr, i.e. a male guardian who marries off the bride. This is usually the father.

3. Two male witnesses.

4. The mahr (dowry), i.e. security money/ wealth, given by the groom to the bride (not the other way round!)

5. An Imam or a knowledgeable Muslim male who seals the contract between the two by making sure all conditions of the marriage contract is fulfilled. And then ends with a khutba (sermon) and du’a for the bride and groom.

Without fulfilling any of the above five conditions of the marriage contract, the marriage will either be invalid or incomplete (depending on which condition was not met).

Doing walima (a public declaration of the union to family and friends by inviting them to food) is recommended action since the prophet (pbuh) used to do it.

Here is a very good link to learn about the differences in Muslim marriage customs from country to country.

Please note: not all Muslim marriage customs are within Islamic values or the shariah. Ask me here if you have doubts about anything particular. I promise only to give you the Islamic opinion.