The “standard model” (sometimes called the “concordance” model) of cosmology posits that:
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General relativity is the correct theory of gravity
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There exist stuff that interacts purely (or almost purely) gravitationally called dark matter
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Further, these dark matter is cold, i.e., it does not move quickly (to understand this nomenclature you can think of hot air, for example, possessing particles that move faster than cold air)
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There exist stuff that interacts gravitationally to accelerate the expansion of the universe, this stuff is called dark energy
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Further, the amount of this dark energy is the same everywhere, i.e., a constant; this leads to the dark energy in this model being called a cosmological constant (the value of this constant is often written as the Greek letter lambda, Λ)
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Finally, there is all the usual matter and fields that we are used to (e.g., atoms, photons, etc)
Combining the stuff I wrote in bold leads to the official name for the “standard model” of cosmology, which is the ΛCDM-model (Λ for the cosmological constant dark energy and CDM being the abbreviation of “cold dark matter”).
Inflation is not technically part of this model, but an extension of it.
Edit: Whoops, of course I forgot the assumption of the ΛCDM-model that is most germane in this thread:
- The universe is, at large scales, the same everywhere (spatially homogenous) and the same in every direction (spatially isotropic)