This term comes from the Arabic "zahr" . And it refers to all those facts or circumstances that have no explanation, they simply happen without prior notice, good or bad things can happen to a person without being able to predict it, which is why it happens randomly.
For example, if a person goes and buys a lottery ticket and it is a winner, this will represent something unexpected for this person, so chance played an important role for this to happen, another example would be that in a classroom one of the students have not studied the topic assigned by their teacher, and the time comes for questions and suddenly the teacher names the one who did not study to explain the topic. Anything can happen, people cannot predict what will happen.
When a random event occurs it is because it happened unexpectedly, by chance. The results of any game will be determined by chance, a person can win or lose a game, without being able to guess what will happen, everything will depend on how lucky they are at that time. The probability and statistics are topics covered in the mathematical sciences and closely related to chance, since statistics focus on randomness.
Chance is based on chance, that is, there are no causes that originate a specific event, however, the philosophical theory of determinism considers that every event has a cause that originates it, and that the fact that it is not specified that it was the What reason the phenomenon happened does not mean that it does not exist.