In investing, it refers to an asset's sale price agreed upon by a willing buyer and seller, assuming both parties are knowledgeable and enter the transaction freely. For example, securities have a fair value that's determined by a market where they are traded.
In accounting, fair value represents the estimated worth of various assets and liabilities that must be listed on a company's books.
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Fair value is a broad measure of an asset's intrinsic worthwhile market value refers solely to the price of an asset in the marketplace as determined by the laws of demand and supply. As such, fair value is most often used to gauge the true worth of an asset.
Also, the fair value of an asset tends to be more static, especially in the context of financial statements, while its market value is at the whims of market forces.