What is merisik and what is its etiquette?

Merisik is the first step of asking informally whether a woman is still free and willing to receive a proposal.
In Malay custom, a representative of the man's family comes to ask about the woman's status (not yet spoken for, not yet proposed to), her family background and her willingness. In Shariah terms, merisik is in line with the advice to make sure the woman is not under another man's proposal, not in her ʿiddah, and suitable in terms of religion and character. Its etiquette: send a respected representative, converse politely, do not press for an immediate answer, and keep the findings confidential if it does not go ahead. If the outcome is positive, then the formal proposal is made. See khitbah.