Inlay is a decorative technique of inserting pieces of contrasting, often coloured materials into depressions in a base object to form patterns or pictures that normally are flush with the matrix. In a wood matrix, inlays commonly use wood veneers, but other materials like shells, mother-of-pearl, horn or ivory may also be used. Pietre dure, or coloured stones inlaid in white or black marbles, and inlays of precious metals in a base metal matrix are other forms of inlay. Master craftsmen who make custom knives continue a tradition of ancient techniques of inlaying precious metals; additionally, many new techniques which use contemporary tools have also been developed and utilized as well by artisans.
Inlay in wood furniture differs from marquetry, a similar technique that largely replaced it in high-style European furniture during the 17th century, in that marquetry is an assembly of veneers applied over the entire surface of an object, whereas inlay consists of small pieces inserted on the bed of cut spaces in the base material, of which most remains visible.
Inlay is commonly used in production of decorative furniture, where pieces of coloured wood or metal are inserted into the surface of the carcass. Lutherie inlays are frequently used as decoration and marking on musical instruments, particularly the smaller strings.
The most famous example of furniture inlay in Europe may be the late 15th century Studiolo  made for Federico da Montefeltro in his Ducal Palace at Urbino, in which trompe-l'oeil shelving seems to carry books, papers, curios and mathematical instruments, in eye-deceiving perspective. The similar private study made for him at Gubbio is now in the Metropolitan Museum of Art (illustration).
Kinds of Inlays 
Egyptian basin with silver inlay
(Walters Art Museum)
- Oxford Companion to the Decorative Arts, 1975, s.v. "Inlay", "Wood-working (Special Techniques)".
- John Fleming and Hugh Honour, The Penguin Dictionary of Decorative Arts (1977) s.v. "Inlay".
- Metropolitan Museum: Studiolo
See also 
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- Contemporary Wall Art Marquetry - New technics
- Luigi Nebuloni's Personal Page Modern inlay painting
- Difference between Indian Classic Inlay and Italian Pietra Dura "Parchinkari"
- Taraceas Spanish wood inlays