A language is a system of visual, auditory, or tactile symbols of communication and the rules used to manipulate them. Language can also refer to the use of such systems as a general phenomenon. Language is considered to be an exclusively human mode of communication; although other animals make use of quite sophisticated communicative systems, none of these are known to make use of all of the properties that linguists use to define language.
A set of agreed-upon symbols is only one feature of written language; all languages must define the structural relationships between these symbols in a system of grammar. Rules of grammar are what distinguish language from other forms of communication. They allow a finite set of symbols to be manipulated to create a potentially infinite number of grammatical utterances.
Another property of language is that the symbols used are arbitrary. Any concept or grammatical rule can be mapped onto a symbol. Most languages make use of sound, but the combinations of sounds used do not have any inherent meaning – they are merely an agreed-upon convention to represent a certain thing by users of that language. For instance, there is nothing about the Spanish word nada itself that force Spanish speakers to use it to mean “nothing”. Another set of sounds – for example, English nothing – could equally be used to represent the same concept. Nevertheless, all Spanish speakers have memorized that meaning for that sound pattern. But for Croatian, Serbian/Kosovan or Bosnian speakers, nada means “hope”.
However, even though in principle the symbols are arbitrary, this does not mean that a language cannot have symbols that are iconic of what they stand for. Words such as “meow” sound similar to what they represent, but they do not necessarily have to do so in order to be understood. Many languages use different onomatopoeias as the agreed convention to represent the sounds a cat makes.
