No phenomenon or event occurs isolated, in a vacuum. No word is used "in itself" - whatever else. Context is a term of Latin origin (Latin contextus). It denotes relations, connections, surroundings.
It is difficult to find a sphere where this phenomenon would not find application, where it would be insignificant. The word in the context can acquire a variety of meanings, shades of meaning - up to the opposite (for example, if it was used with irony or sarcasm). In language, as in interpersonal communication, the interpretation of a passage of a text, speech or expression depends on what was said (meant) before and after. For example, for the word "sea" the direct context is a large amount of water, but saying "the sandy sea", we mean the desert. Lexem is used here as a metaphor. The meaning of the word "sea" is here perceived as a synonym for "huge amount", "something immense".
In the sphere of verbal communication, ignoring the "environment", the atmosphere, the situation of conversation can lead not only to misunderstandings, but also to conflicts. In addition, the cultural context is extremely important in this field. This is often a decisive factor that can completely distort the course of the conversation and further developments. For example, in France, when greeted, a completely normal phenomenon will be kissing the cheek even among unfamiliar people. And in Japan or the UK such a gesture will be perceived as unnatural, too intimate.
In linguistics in the study of human communication, we are mainly talking about the phraseological context (the meaning of the phrase and idiom), as well as the situational one. In the case of the latter, factors such as time, space, sphere are important: business negotiations, lecture, family conversation, TV debates, as well as events preceding the conversation. Significant also are the participants in the communication process and the roles that are assigned to them, for example: a mentor, a friend, a lover. The situational context is also the goals, plans, intentions and knowledge of the interlocutors. It is not always obvious, but the underlying "currents", such as thoughts and feelings of the opponent, are extremely important for understanding the essence of the whole. For example, in a discussion about the fate of prisoners, people who have experience in prison or in custody, and those who have been victims of crime, will behave differently in different ways.
Other sciences use this word to express the connections (sometimes quite remote) of certain events or phenomena. The context in literature can be historical, artistic, and ideological. No work exists outside of time and space. Of course, the degree of accuracy of the transfer of realities is completely different, depending on the genus and genre. However, in poetry and prose, the atmosphere of time, values, ideology is present. Buninsky "Dark alleys" reproduce not only pre-revolutionary Russia, but also the life of the Parisian emigration. And in Tolstoy's War and Peace, the cultural and historical context is the tenth-twentieth years of the nineteenth century. In the environment of certain concepts, allusions (a hint of a fact or an object not directly named), words acquire a new meaning. Symbols can be interpreted only in the macro context - that is, on the scale of the whole work, the writer's full creativity, epoch, direction. Certain phenomena can be perceived in their entirety only in connection with the biography of the author or his ideology. For example, the Voronezh context is for Osip Mandelstam the place of exile, it is no coincidence that the associative series associated with this city reminds us of something gloomy, harsh: "Voronezh is a raven, a knife." Only knowing the life of the poet, we can decipher these symbols. Any word in the context can activate its portable or peripheral meaning.