Fat can be categorised into four main categories; subcutaneous, inter-muscular, intra-muscular and inter-cellular.
Subcutaineous (under the skin) and kidney fat: These are harder, higher melting-point fats which are less ‘good for you’, as they contain higher amounts of saturated fats.  Animals which grow quickly (typically feedlot animals) will put fat down at these sites early.
Inter-muscular fat (or ‘seam’) fat: This can be found between the muscle seams, and is sometimes mistaken for intra-muscular fat.  A slightly better-quality fat to eat.
Intra-muscular fat (marbling): This is what has been firmly intrenched in consumer’s minds to be what to look for when buying a steak.  Yes, it can be a great indicator of meat quality, but unfortunately many other eating quality attributes are often not considered.  With marbling, the finer the ‘fleck’ the better quality.
Inter-Cellular fat: This is the really good stuff and it is often overlooked, as it is not really visible to the eye. Inter-Cellular fat is much more prevalent on slower-growing pasture-raised cattle, has a lower melting point, much less saturated fats/VFA’s, and higher in omega 3 and nutrients generally. This is where the great flavour is.