A pattern is a repeating set of events or objects that is identifiable and to some degree predictable. The repetition can be exact or approximate. Some common examples include repeating wallpaper designs (typically exact) and the seasons of the year (approximate). Patterns can also be more abstract or conceptual, in which case they may be called heuristics; one example might be the idea that "history repeats itself".
Humans are exceptionally good at detecting patterns, leading to a common description of our species as "pattern-seeking animals". It is this tendency that underlies almost every special ability humans possess: symbolic thought, pervasive tool use, complex language and mathematics, detailed "theories of the world" (including, for example, scientific knowledge), and so forth.