single vs. double bevel

every knife edge is made of bevels – the angled surfaces that meet at the edge.
the question is: on one side, or on both?

double bevel (ryoba). ground on both sides.
almost every western knife, and most japanese knives you'll find in a home kitchen – gyuto, santoku, bunka.
all-rounders.
they cut straight and work for left- and right-handers alike.

single bevel (kataba). ground on one side only.
the front (omote) has one wide bevel (kireha), ending in a clear line (shinogi).
the back (ura) is flat with a slight hollow (urasuki), framed by a thin flat rim (uraoshi).
a traditional japanese build – yanagiba for fish, deba for breaking down fish, usuba for vegetables.
made for one job, done perfectly.

why single bevel? it can be made extremely sharp and leaves a glassy cut surface.
perfect for raw fish and paper-thin slices.

why not? it's made for one hand – there are right- and left-handed versions.
it tends to steer while cutting, needs practice, and is harder to sharpen.

and the micro bevel? almost every edge gets one – a tiny second bevel right at the very edge.
barely visible, but it makes the edge tougher.
on single and double bevel knives alike.
more on that in its own entry.