Feeding for Dummies

Hello,

Can someone please break feeding down to the most basic of basic terms.

The starter I have states to take it out, feed it however much water and flour to get it the size you want for your recipe (water and flour til it’s the consistency it was when it was first opened) let sit overnight, put 1 cup back in the jar and bake with the rest.

Is this correct? This would mean there is no discard and most things I’ve seen online say to do 1:1:1, leave it out for 2hrs then put it back in the fridge to save it. Not let it sit overnight then put it in the fridge.

I did the whole feed, leave overnight, save 1 cup, then bake with the rest a week ago and tried to do the same this week but this time my starter was not active and bubbly, it had a whole bunch of water on top then seemed to have some starter looking solution underneath. Not positive if it would’ve been okay under all that water as I discarded it to buy another once I thought it was ruined.

Thank you for all your help!