“The medium is the message,” a statement made by Marshall McLuhan way back in 1964, is among the first and most famous quotes in the study of media and information. McLuhan was studying how culture and society are affected by the means with which information is conveyed. According to McLuhan, media affect us not only through the information that they deliver but also through their language, codes, and conventions. Think about how the advent of social media has changed the way we communicate with the people around us and quickened the pace of everyday life. In this sense, media are rendered with more power and more significance, and are hence worthy of being studied critically.
According to UNESCO, to be media and information literate, one must know how information, ideas, and meanings are communicated. This means being able to understand the “language” or “grammar” of each medium or information provider. In a way then, learning the “codes” and “conventions” used by media practitioners to communicate an idea or a message is like learning a new language.
There are various types of codes in media. These technical and symbolic codes are used to communicate with audiences and send kinds of messages. Here are some of the codes used in media:

These categories, however, are not mutually exclusive. To convey power, for example, filmmakers make use of technical, written, audio, and symbolic codes. Also, technical, written, and audio codes are oftentimes used as symbolic codes. Understanding how a media material utilizes codes to communicate a message equips us with the capacity to evaluate information more critically.
Media conventions are referred to as the generally accepted ways of doing something. Each genre in television, film, and literature follow certain conventions that distinguish them from other genres.
We can differentiate a TV series from a news program because both follow different sets of media conventions. All of these, along with media codes, make effective communication between media and the audience a lot easier.