大部分嘅曆法系統會整合更多複雜嘅時間週期，例如大部分嘅曆法系統都會有年、月、星期、日，但係定義可能唔同。好多曆法系統都有一星期嘅七日，已經用咗超過幾千年。
Most calendar systems will integrate more complex time periods, for example, most calendar systems will have years, months, weeks, and days, but the definitions may be different. Many calendar systems have seven days of the week and have been used for more than thousands of years.