Hello is a bridge

Contract bridge

Contract bridge, usually known simply as bridge, is a trick-taking card game using a standard deck of 52 playing cards played by four players in two competing partnerships with partners sitting opposite each other around a small table...

 convention used for intervention over an opponent's 1NT opening. It allows for all one- and two-suited hands to be shown, and - for one suited hands - retains the ability to transfer

Jacoby transfer

The Jacoby transfer, or simply "transfers", in the card game contract bridge, is a convention initiated by responder following partner's notrump opening bid that requests opener rebid in the suit ranked just above that bid by responder, i.e...

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It features the following calls:

• Double is for penalty
• 2 shows diamonds or a major-minor two suiter
  Two suiter
  In contract bridge, a two suiter is a hand containing cards mostly from two of the four suits. Traditionally a hand is considered a two suiter if it contains at least ten cards in two suits, with the two suits not differing in length by more than one card. Depending on suit quality and partnership...
  
  . Responder transfers to 2 which is either passed or advanced (diamond suit) or a major is bid (2 suiter, unspecified minor)
• 2 is a transfer to hearts
• 2 shows both majors (responder may pass or adjust
  Pass-or-correct bid
  In the card game bridge a pass-or-correct bid , is a non-forcing bid that asks partner to pass or bid differently based on her/his holding...
  
  to 2)
• 2 shows spades (natural bid)
• 2NT is a transfer to clubs
• 3 shows both minors (responder may pass or adjust to 3)
• 3 shows both majors with massive playing strength (responder takes a preference to 3 or 3, or jumps to 4 or 4 with supporting values)

By design, in many cases, the advancer will become declarer, thus placing the strong 1NT hand on opening lead.

The convention is named for two of its inventors, Jerry Helms and Bill Lohmann.