Not all elementary particles have mass, but the ones that do are typically referred to as massive particles. For example, particles like the electron, muon, and quarks have mass, while particles like the photon and gluon are massless.
As for dark matter, its exact nature and composition are still unknown. Dark matter is a hypothetical form of matter that does not interact with light or other electromagnetic radiation, making it difficult to directly detect. However, its existence is inferred from its gravitational effects on visible matter and the large-scale structure of the universe.
Based on current observational evidence, dark matter is believed to have mass. In fact, one of the key reasons dark matter is postulated is to explain the observed gravitational effects that cannot be accounted for by visible matter alone. The mass of dark matter is estimated to be significantly larger than that of visible matter.
Observations from various sources, such as the cosmic microwave background radiation and galaxy rotation curves, suggest that the total mass in the universe is predominantly composed of dark matter. It is estimated that dark matter makes up about 27% of the total mass-energy content of the universe, while visible matter, including stars, galaxies, and interstellar gas, accounts for only around 5% of the total mass-energy. The remaining 68% is attributed to a mysterious form of energy called dark energy.
It's important to note that these estimates are based on our current understanding and observational data, which are subject to refinement as scientific knowledge progresses. Further research and observations are ongoing to better understand the properties and nature of dark matter and its overall contribution to the mass of the universe.