The validity period of this ticket is one week.
契約期間は来年の三月までです。
The contract term runs until March of next year.
The application period has already passed.
The company decided to extend the campaign period.
Many items sold during the sale period.
We have set a period for returns.
期間 refers to any span of time, while 周期 specifically implies a regular, repeating interval.
期間 is a general span of time (e.g., 夏休み期間), whereas 期限 often implies a limit or expiration point.
期間 is a neutral, often formal term for a fixed 'period' or 'term' (as in a contract), whereas 一時期 highlights a personal or transient phase.
期間 is a broader term for a span of time that need not be measured in years, whereas 年数 always counts whole years.
期間 refers to a fixed span between a start and end date, while 時間 is the more general word for time, duration, or hours.
fixed-term factory worker; contract factory worker
fixed period; fixed interval