Operations is the building in the middle of your starbase, and its level is what people mean by 'Ops 24' or 'Ops 39'. Two things follow from it. First, nothing else on your base can be upgraded above your Operations level, so Operations is always the bottleneck you raise before anything else can catch up. Second, most new buildings do not appear until Operations reaches a specific level. That second point is what this guide is about: knowing what is coming means you stop wasting resources on things that are about to be replaced.
At Operations 1 you already have Operations itself, the Academy (where officers live when they are not on a ship), Parsteel Generator A and the Parsteel Warehouse, Drydock A, and Defense Platform A. That is the whole early loop in miniature: generate a resource, store it, park a ship, defend the base.
Between Operations 2 and 12 you unlock, in order: Parsteel Generator B at Ops 2, the R&D Department at Ops 4, then a big step at Ops 5 with the Shipyard, the Tactical Deck and five more drydocks (B through F) all at once. Tritanium arrives at Ops 6 with its generator and warehouse. The Shuttle Bay lands at Ops 8, which is what turns on Away Team Assignments. Ops 9 gives you the Astronautics Studio, where new ship hulls are researched before the Shipyard can build them. Ops 10 brings Dilithium — generator and warehouse — plus the Refinery.
If you only plan around three of those, make them these. The R&D Department at Ops 4 is where research happens, and research is the single largest long-term source of power in the game. The Refinery at Ops 10 turns the raw ore, crystal and gas you mine into the refined materials that ship and building upgrades actually consume — before it, mining has nowhere to go. The Shuttle Bay at Ops 8 opens Away Team Assignments, which generate rewards from officers who would otherwise be idle.
You get Drydock A at Ops 1 and then a jump: B, C, D, E and F all unlock together at Ops 5. After that there is a long gap. Drydock G does not appear until Ops 30 and Drydock H until Ops 35. So the number of ships you can have active barely changes for twenty-five levels. Plan your fleet around the ships you have rather than waiting for more slots.
Look at the maximum level column on the buildings list and you will see two groups. Core buildings — Operations, the generators, warehouses, drydocks, the Shipyard, the Refinery, the Academy — cap at level 80. A second group, including the Tactical Deck, EPS Distributors, the Exographic Targeting Arrays and the plasma harvesters and vaults, caps at 34. That cap is a useful signal: a building that stops at 34 is one you will finish and never think about again, so there is no reason to drip-feed it.
The buildings page is sorted by the Operations level that unlocks each one, so reading it top to bottom is reading your own progression in order. Each building's page carries its in-game description, the level it unlocks at, and how far it upgrades. If you are deciding what to build next, that ordering answers it faster than any tier list.