Only two elements are liquid at standard conditions for temperature and pressure: mercury and bromine. Four more elements have melting points slightly above room temperature: francium, caesium, gallium and rubidium. In addition, certain mixtures of elements are liquid at room temperature, even if the individual elements are solid under the same conditions (see eutectic mixture). An example is the sodium-potassium metal alloy NaK. Other metal alloys that are liquid at room temperature include galinstan, which is a gallium-indium-tin alloy that melts at , as well as some amalgams (alloys involving mercury).
Pure substances that are liquid under normal conditions include water, ethanol and many other organic solvents. Liquid water is of vital importance in chemistry and biology, and it is necessary for all known forms of life.
Inorganic liquids include water, magma, inorganic nonaqueous solvents and many acids.
Important everyday liquids include aqueous solutions like household bleach, other mixtures of different substances such as mineral oil and gasoline, emulsions like vinaigrette or mayonnaise, suspensions like blood, and colloids like paint and milk.
Many gases can be liquefied by cooling, producing liquids such as liquid oxygen, liquid nitrogen, liquid hydrogen and liquid helium. Not all gases can be liquified at atmospheric pressure, however. Carbon dioxide, for example, can only be liquified at pressures above 5.1 atm.
Some materials cannot be classified within the classical three states of matter. For example, liquid crystals (used in liquid-crystal displays) possess both solid-like and liquid-like properties, and belong to their own state of matter distinct from either liquid or solid.