This is a mod that lets you change the direction that gravity moves players.
It was originally produced as part of The Modding Trials where it was just known as Up And Down, and only allowed players to flip the gravity such that they 'fell' upwards.
Up And Down And All Around (Up And Down for short) allow players to change the direction of their gravity to any of the cardinal directions (up, down, north, east, south and west).
If you are using this mod with galacticraft/advanced rocketry or other mods that take you above y=255, you will want to edit the config so that you don't take damage/die when above y=255, see https://minecraft.curseforge.com/projects/up-and-down-and-all-around?comment=18 for details on these config changes.
Gravity Generators change players' gravity in an area.
Gravity Controllers change your gravity when they're in your inventory and allow you to change gravity direction at will.
Gravity Anchors cannot have their direction changed, but they are cheap to craft and overpower other early-game sources of gravity. Take care when crafting them as they will take effect the instant you pick them up out of a crafting table.
Baubles render at weird angles when under the effect of non-downwards gravity.
Elytra don't work properly when under the effect of non-downwards gravity.