Conversation is a form of interactive, spontaneous communication between two or more people. Typically it occurs in spoken communication, as written exchanges are usually not referred to as conversations. The development of conversational skills and etiquette is an important part of socialization. The development of conversational skills in a new language is a frequent focus of language teaching and learning.
Conversation analysis is a branch of sociology which studies the structure and organization of human interaction, with a more specific focus on conversational interaction.
Definition and characterization
No generally accepted definition of conversation exists, beyond the fact that a conversation involves at least two people talking together. Consequently, the term is often defined by what it is not. A ritualized exchange such a mutual greeting is not a conversation, and an interaction that includes a marked status differential (such as a boss giving orders) is also not a conversation. An interaction with a tightly focused topic or purpose is also generally not considered a conversation. Summarizing these properties, one authority writes that "Conversation is the kind of speech that happens informally, symmetrically, and for the purposes of establishing and maintaining social ties."
If (L, ≤) is a partially ordered set (poset), and S⊆L is an arbitrary subset, then an element u∈L is said to be an upper bound of S if
s≤u for each s∈S. A set may have many upper bounds, or none at all. An upper bound u of S is said to be its least upper bound, or join, or supremum, if u≤x for each upper bound x of S. A set need not have a least upper bound, but it cannot have more than one. Dually, l∈L is said to be a lower bound of S if l≤s for each s∈S. A lower bound l of S is said to be its greatest lower bound, or meet, or infimum, if x≤l for each lower bound x of S. A set may have many lower bounds, or none at all, but can have at most one greatest lower bound.