Ecru is a color closely related to beige -- in fact, most of us would consider it beige. Until the 1930s it was used as a synonym for beige, although it had a very specific overtone; fancy but unfinished. Ecru comes from the French écru, meaning 'raw', or, in the case of fabrics, 'unbleached'. Ecru is traditionally the color of unbleached finer fabrics, particularly linen and silk. (This is in contrast to beige, which is traditionally the color of unbleached wool and cotton).
These days ecru is used for shades of greyish-pale yellow or pale greyish-yellowish brown. As such, it is easily confused with beige, khaki, taupe, and tan.
Ecru's hex triplet is #C2B280, its sRGB coordinates are R194, G178, B128.