## Types of Contiguity

When a tile touches another tile, it is said to be contiguous. There are two types of contiguity that can occur on square-tile maps. There is adjacency which is called ADJACENT, and then there is cardinal adjacency, referred to as CARDINALLY ADJACENT.

These two types of tile contiguity are not the same: all cardinally adjacent tiles are also adjacent. But not all adjacent tiles are cardinally adjacent. This is clarified in the diagrams below.

Adjacent tiles are any of the 8 tiles that touch the tile in question. Adjacent tiles may also be referred to as 8-adjacent. In the image below:

• The blue tile is the tile in question.
• The green tiles are adjacent.

Cardinally Adjacent tiles are the 4 tiles that directly touch the tile in question, not including the corners. Cardinal Adjacency gets its name from the "four cardinal directions" of North, South, East, and West. In the image below:

• The blue tile is the tile in question.
• The green tiles are cardinally adjacent.
• White tiles are not cardinally-adjacent.

Diagonally adjacent tiles touch a given tile diagonally. This is just an easier way to say "adjacent tiles which don't qualify as cardinally adjacent."

In the image below:

• The blue tile is the tile in question.
• The green tiles are diagonally adjacent.
• White tiles are not diagonally adjacent.