Sometimes you have a hand so powerful that you want to be sure partner responds.
The only opening bid that is forcing on partner is an opening 2♣.

2♣ OPENING REQUIREMENT
• a hand with 22 or more points, or
• a hand that contains enough playing tricks to be within one of game (you have a long suit)

RESPONSES TO 2♣ OPENING (steps system)
• 0-3 points : bid 2♦
• 4-6 points : bid 2♥
• 7-9 points : bid 2♠
• 10-12 points : bid 2NT
• continue pattern

RESPONSES TO 2♣ OPENING (2♦ waiting system)
• 0-7 points : bid 2♦
• 8+ points : bid 2 of a 5+ card suit, especially a Major suit
• 8+ points : bid 2NT with no 5+ card suit

OPENER'S SECOND BID
• 22-24 points : bid 2NT with a balanced hand
• 25-26 points : bid 3NT with a balanced hand
• otherwise : bid best suit, trying to find a fit with partner

RESPONDER'S SECOND BID
• if Opener rebids 2NT or 3NT you may pass with a poor hand
• if Opener rebids in a suit you may not pass, even with a poor hand. Support with 3 cards.