I love love love subway tile. bathrooms. kitchens. laundry rooms. floors. walls. range hoods. Traditionally subway tile is 3" x 6" originating in the early 1900's in NYC subway stations, but now they widely vary in size and material. Technically as long as it is rectangle and not square it could be considered subway, but if you want to keep it somewhat traditional, even if its in a color besides white, I would pick one that the height is half the length, whether it is typical 3" x 6" or larger or smaller, there is also such a thing as "mini" subway tile. For a more modern look you can choose an elongated subway tile. You can also consider choosing a contrasting grout so each individual tile stands out from the other. It also doesn't have to be laid in the traditional horizontal brick pattern, you'll see a couple variations below...
|DE GIULIO KITCHEN DESIGN|
The kitchen above has a sliding subway back splash to conceal storage. So smart!
|DE GIULUO KITCHEN DESIGN|
|DESIRE TO INSPIRE|
I love the subway tiled hood!
|URBAN GRACE INTERIORS|
These traditional subway tiles were laid in a herringbone pattern
Mini Subway Tile