As a layman, I have come to understand basic expansion (meaning without dark energy) as objects which are not locally gravitationally bound are moving away from each other due to some inertia created from an initial period of inflation. This rate of recession is the Hubble constant and it changes over time as the universe has changed from being radiation / matter dominated and the energy density has diluted over time with expansion. However, there are no ‘forces’ acting upon these objects causing them to recede and space is not a physical thing that expands causing this recession. There is however also Dark energy, which can be modelled as a force which causes this rate of expansion to accelerate. Dark energy being like a scalar field which means it’s energy density doesn’t dilute with expansion. So as these objects recede, there are greater distances between them and hence more dark energy between them, so more ‘force’ and this is what causes the rate of expansion to accelerate at greater distances. However, I also read that a lot that ‘space’ itself is expanding and this expanding space has physical consequences. The most frequent references to this are: 1. cosmological redshift, which explains that the wave length of a photon is ‘stretched’ due to space expanding. 2. Recession velocities are allowed to be >c because recession is not ‘proper motion’ it is caused by space between objects growing. 3. Light from distant galaxies which are receding from us at speeds >c will never reach us as the space between them and us is expanding at a rate greater than c. As a counter to those there points I have come to understand the following: As regards to a), cosmological redshift is not from ‘space expanding’ but more from of the system consisting of the emitter, the photon, and the receiver. These posts here and here by Peter in a different thread were very useful for me. As regards b) I started a thread here where I am trying to understand more about how GR allows distant objects to recede >c. Not because of space between them expanding but because of something to do with the curvature of spacetime over large distances allows for recession speeds to be great than c. (Still trying to understand this) As regards c) I have read that light from galaxies moving away from us > will still reach us one day. Which makes sense if there is nothing ‘growing’ in between. So I’d be very grateful for any help to clarify these points and correct my understanding!