(new to blender) i am trying to create a fluid sim in blender 2.83 but in my physics tab under domain there is no 'bake data' button in the options. It's there in all the tutorials i've watched but i dont seem to have it.
It's because the cache type is set by default to "Replay". Replay does not provide any caching at all; it's used for instant replay. If you want to bake data, you should change cache type to modular or final (for final baking all physics)
And don't forget, that you need to save file before any cache type of simulations.
By default the Cache-Type is set to Replay and interactively shows the simulations in realtime.
(depending on your system that is)
marked red the defaults for the "Cache"-sub-Panel and the Type: Replay
There are actually 2 ways for baking:
Changing the Cache-Type to Modular, makes a Bake Data button appear at the bottom of the Settings-Panel. That button bakes and caches the Liquid (if checked) and let's you afterwards bake the Mesh (with it's own button) as well if you so desire (even if Mesh is checked it won't be baked in one go).
red marked, setting the type to "Modal"(1.) displays the Button (2.) for backing
The Cache-Type set to Final on the other hand makes a Bake All button appear in the Cache-Panel and by pressing that one button, the Liquid and if also checked Mesh will be baked/cached in one fell swoop. You can also Free All (If data is cached the button changes) with that same button if needed.
red marked, setting the type to "Final"(1.) displays the "Bake All" (2.) button
Testing/building with "Replay" is the usual approach, thus it is default. I tend to bake the Liquid and Mesh separately aka. "Modular", but once you are set and do not need to make more adjustments, you can use "Final" to safe yourself some clicking and scrolling.