1. Systematicity: Languages are not random collections of sounds or symbols. They have a systematic structure with rules governing how sounds, words, and sentences are put together. This systematicity allows for communication and understanding.
2. Arbitrariness: The relationship between a word and its meaning is largely arbitrary. There's no inherent connection between the sound "cat" and the furry animal it represents. This allows for flexibility and the development of new words.
3. Productivity: Languages are creative systems. They allow speakers to create and understand new sentences and expressions they've never heard before. This is possible due to the underlying grammatical rules and the ability to combine existing elements in novel ways.
4. Displacement: Languages allow speakers to refer to things that are not present in the immediate environment, either spatially or temporally. This allows for communication about the past, future, or distant locations.
These four characteristics highlight the key features that make human language possible and enable us to communicate effectively.