Animated Tiles / Tile Groups

[gameids]

I am new to RPG Maker and I have notices that specific tiles in the editor change their appearance when they are surrounded by the same tile. For example the waterfalls. Depoending on how many waterfall tiles i place, the mid tiles will change, so that only the tiles on the left and right are border tiles.
Moreover the waterfalls are animated.

I have had a look at the corresponding .png file in the img folder and saw that there are tiles for the different states, but I was unable to figure out how such a png-file is composed.
How does the editor know, which tiles are animated, how fast the animation should go, and what tiles are border-tiles or mid-tiles?

I want to create my own tileset- so that is a necessary information for me. I stumbled over the term "autotiles" but I cant find a good tutorial.

Can you post some resourcs on this topic?

[kittylitterproduction]

Open the Help, read the resource specifications. Then look up autotile tutorials.

[gameids]

Very helpful. Thank you!

[Adjorr]

any tile on the A page of a tileset is an auto tile, A1 is where animated tiles go

[kittylitterproduction]

Originally posted by Adjorr:

any tile on the A page of a tileset is an auto tile, A1 is where animated tiles go

A5 aren't autotiles