Room alignment is a very important term because you need to understand it in order to find places where you could execute a skew. It basically means that the source and destination room are connected with each other in a very specific way. The source room needs to share an extended border with the destination room. You can see that in the picture below. The red line is the shared border, S the source room and, D the destination room. For the room alignment it is not important which one is which it just affects how the skew works. Once you understand how it works you can see potential room alignments all over the map.