Dexter and sinister

Dexter and sinister are terms used in heraldry to refer to specific locations in an escutcheon bearing a coat of arms, and to the other elements of an achievement. Dexter (Latin for 'right')[1] indicates the right-hand side of the shield, as regarded by the bearer, i.e. the bearer's proper right, and to the left as seen by the viewer. Sinister (Latin for 'left')[2] indicates the left-hand side as regarded by the bearer – the bearer's proper left, and to the right as seen by the viewer. In vexillology, the equivalent terms are hoist and fly.

Argent a bend sinister gules. The bend sinister extends upward to the sinister corner, while the bend (i.e. bend dexter) extends upward to the dexter corner of a shield.
Division of the heraldic escutcheon: dexter to the bearer's right (viewer's left), the position of honour; sinister to the bearer's left (viewer's right).
The different view points of knight and viewer; the heraldic view is that of the knight. Charges on the shield, like this lion rampant, look to the dexter side unless otherwise stated in the blazon.