Semantics is the study of the meaning of words and sentences. The discipline studies the interpretation of individual words, the construction of sentences and the literal interpretation of text the way it is written. Proper understanding of semantics relates to all academic disciplines in all languages, as a clear understanding allows students and teachers to communicate their messages clearly without fear of misinterpretation.
Scientists gain an understanding of how language is learned through an understanding of semantics. Because semantics is the study of the meaning of words, the study of this discipline is closely related to language acquisition. Students learn language at first by the replication of sounds for verbal speech and images for written. Eventually, however, those sounds and images need to be assigned meaning, which is the area of semantics. People learn the meaning of words in a basic fashion at first, but then as facility with a language grows, more complex meanings emerge. Semantics explains the various types of meaning that exist within a language, granting insight into how a person builds ability and understanding with that language.
Semantics is critical to a language because without it, there would be no real structure to a language. Without the basic, intrinsic understanding of semantics that comes along with language acquisition, speakers could string words together in any order they wanted, and listeners would have a very hard time deriving meaning from those sentences. Semantics provides speakers a structure to use when they need to slot words into sentences, creating meaning.
Relating to Other Disciplines
Semantics is critical because of the way it allows scientists and academics to link language to the other disciplines that it is important in. For instance, the study of the way language is used is very important in psychology. Semantics provides a framework for which to analyze and understand the use of language even in the context of fields outside the strictly linguistic area of study.
Much of the meaning of language is conferred through inferences. Humans write things, and then the reader infers based on the information available to him something about the sentence. Pronouns are a type of inference. For example, in the sentence: "Mark went to the store. He bought some milk," it is not explicitly shown that the second sentence refers to Mark. However, the first sentence makes us infer that it is Mark that bought milk. Writers must understand some degree of semantics to know when their meaning will be properly inferred.