Nikah explained.

The four pillars, and nothing beyond them

A nikah is valid when four things are present. Consent, from both of them, freely given. A wali contracting on the bride's behalf. Two witnesses. And a mahr, the payment that goes to the wife herself.

That is the whole requirement. No venue, no guest list, no card, no photographer, no minimum amount, no set of clothes. Everything a culture adds beyond those four is culture, and it is worth naming as such, because families are routinely told that expenses which have no basis in the contract are religiously required.

The contract itself is a sentence and its answer: an offer, and an acceptance, both heard by the witnesses. It is deliberately short. What makes it weighty is not the length of the wording but what the Qur'an calls it.

A solemn covenant, not a purchase

The Qur'an describes marriage as a mithaqan ghaliza, a solemn covenant, in the same passage that forbids a husband from taking back what he has given. The word is used elsewhere in the Qur'an for the covenants taken from the prophets. It is not decorative.

The verse most quoted about marriage names what it is for: tranquility, and affection, and mercy placed between the two of them. That is the stated purpose, and it is a reasonable test to hold a proposal against. A match that cannot plausibly produce those three is not made suitable by meeting the four formal conditions.

What a nikah is not

It is not a courtship. There is no stage in the Sunnah where a man and a woman spend months getting to know each other privately and then decide. The looking that is permitted is a look, with a purpose, and the knowing that is permitted happens through the families and in the presence of others.

It is not a purchase. The mahr belongs to the wife and to nobody else, and a father who takes it has taken something that was not his. The Qur'an is explicit that a husband may not reclaim it, even a great amount of it, when a marriage ends.

It is not a private arrangement. The two witnesses exist so that a marriage is known. A relationship no one can attest to is the thing the contract was designed to be distinguishable from.

Choosing, and what to choose for

The best-known guidance on choosing is agreed upon and short: a woman is married for four things, her wealth, her family standing, her beauty and her religion, and the one to choose is religion. It is worth noting what the hadith does not say. It does not say the other three are illegitimate. It says which one decides when they compete.

The corresponding practical instruction to young men is equally plain: whoever among you is able to marry should marry. The obstacle in most eras has not been willingness but access, and that is the narrow problem a matrimonial platform is actually able to solve.