In semiotics, the value of a sign depends on its position and relations in the system of signification and upon the particular codes being used.

Value is the sign as it is determined by the other signs in a semiotic system. For linguist Ferdinand de Saussure, for example, the content of a sign in linguistics is ultimately determined and delimited not by its internal content, but by what surrounds it: the synonyms redouter ("to dread"), craindre ("to fear"), and avoir peur ("to be afraid") have their particular values because they exist in opposition to one another. If two of the terms disappeared, then the remaining sign would take on their roles, become vaguer, less articulate, and lose its "extra something" because it would have nothing to distinguish itself from.

For de Saussure, this suggests that thought is a chaotic nebula until linguistic structure dissects it and holds its divisions in equilibriums. This is akin to the philosophy of Sir William Hamilton, who indirectly influenced Saussure and believed that the mind could only grasp an idea through distinguishing it from something that it is not. He reasoned that the two objects would otherwise collapse together for the mind and become indistinguishable from one another.

Value determines the sign as a whole, not just meaning. Sound is also an indeterminate nebulous. The arbitrary nature of the sign and the flexibility of sound means that an agreed upon contrast is required. For example, "zena" is useful because it stands in contrast to "zenb" within an agreed upon system. Without the distinction, "zena" could be used for absolutely anything, or indeed nothing, making communication an impossibility.

It is only the sign as a whole that has value. Linguistic structure simultaneously unites sound with thought and decomposes "thought-sound" into linguistic units, or signs, consisting of a signifier and a signified (sound-pattern and concept, respectively). When analysed in isolation, the sound-pattern or concept are pure differences, emerging from series of sound-patterns or concepts that they themselves are dependent upon. But in isolation, they are mere abstractions, because neither can exist without the connection between the two. It is the sign as a whole, then, that is the concrete entity of structural linguistics, which is not a pure difference, a negative term, but a pure value, a positive term that is merely in opposition or resistance to all the other signs in the system.

Drawing from the original definition proposed by Saussure (1857–1913), a sign has two parts:

This emphasises that the sign is merely a symbol for the class of object referred to. Hence, the lexical word or noun "box" evokes a range of possibility from cheap card to gold-encrusted container. The reader or audience may not be able to see the particular box referred to but will be aware of its likely form from the other signs accompanying the use of the particular word.

However, there is no necessary connection between the signifier and the signified. There is nothing inherently boxy about the component sounds or letters that comprise the noun "box"—the scope of onomatopoeia is limited when forming a language. All that is necessary is that the relevant group of people should decide to use that word to denote the object. Evidence that this is the correct view comes from the fact that each language can encode signifiers with whichever signified they wish to communicate. Hence, for example, the letters comprising "air" signify what humans breathe in English, and what fish breathe in Malay, i.e. water.