# What's the difference between Tiled maps' various tilewidth/tileheight values?

I'm parsing Tiled maps (.tmx) for my game, and even after reading the documentation, I don't understand what the difference is between the attributes tilewidth and tileheight of the map element versus the attributes of the same name in the tileset element. They are often the same; an example where they differ is the map _isometric_grass_and_water.tmx_ from Tiled's examples folder:

<map version="1.0" orientation="isometric" width="25" height="25" tilewidth="64" tileheight="32">
<tileset firstgid="1" name="isometric_grass_and_water" tilewidth="64" tileheight="64">


Also, there's this child element of tileset whose purpose I don't understand:

    <tileoffset x="0" y="16"/>


Do those distinct values exist for isometric maps? If anyone could shed some light on this, my hurty brain'd be very thankful.