没有 (méi yǒu) is the standard Mandarin negation of 'to have' or 'there is/are'. It functions as a single verbal unit meaning 'to not have' when followed by a noun (e.g., 没有钱 — 'to not have money'), and 'there is not / there are not' when used existentially (e.g., 没有猫 — 'there is no cat'). Unlike English, it cannot be split — the two characters always appear together as one phrase. The character 没 originally meant 'to sink' but evolved to indicate absence; 有 means 'to have', so together they form a clear, emphatic negation of possession or existence.

This word is extremely common in daily speech and writing, used across all registers — from casual conversation to formal documents. It’s essential for expressing lack, denial of facts, or non-existence. Note that 没有 cannot be used to negate action verbs in the past (for that, use 没 + verb); it only negates 有 or existential statements. It also serves as a polite, soft way to say 'no' in responses (e.g., Question: 'You’re coming?' Answer: '没有' — 'No, I’m not.') — though this usage implies 'I don’t have [the ability/time/intention]', not just a flat denial.