For example:
* "The dog (a golden retriever) was very friendly." The parentheses are used to set off the breed of the dog, which is explanatory information.
* "The meeting was scheduled for 3 p.m. (Eastern Time)." The parentheses are used to clarify the time zone.
You can also use dashes or commas for this purpose, depending on the context.
* "The dog—a golden retriever—was very friendly."
* "The meeting was scheduled for 3 p.m., Eastern Time."
However, parentheses are generally preferred when you want to add a less intrusive or less emphatic explanation.