In the game of 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...

 Ekren refers to a preempt

Preempt

Preempt is a bid in contract bridge whose primary objectives are to thwart opponents ability to bid to their best contract, with some safety, and to fully describe one's hand to one's partner in a single bid. A preemptive bid is usually made by jumping, i.e. skipping one or more bidding levels...

ive opening of 2 defined as 4-4, 4-5, 5-4 or 5-5 in the majors

Major suit

In the card game contract bridge, the major suits are spades and hearts . The major suits are of prime importance for tactics and scoring as they outrank the minor suits while bidding and also outscore them...

 and 3-10 hcp

Hand evaluation

In contract bridge, various bidding systems have been devised to enable partners to describe their hands to each other so that they may reach the optimum contract. Key to this process is that players evaluate and re-evaluate the trick-taking potential of their hands as the auction proceeds and...

. This conventional preempt

Preempt

Preempt is a bid in contract bridge whose primary objectives are to thwart opponents ability to bid to their best contract, with some safety, and to fully describe one's hand to one's partner in a single bid. A preemptive bid is usually made by jumping, i.e. skipping one or more bidding levels...

 was designed by Bjørn Olav Ekren from Norway

Norway

Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

. It can be seen as an example of the modern style of ultra aggressive preemptive bidding.
Responses to a 2 Ekren opening :

Pass = To play (can be a tactical manoeuvre in the absence of a major suit fit and does not guarantee long diamonds)

2/ = To play

2NT = Relay (invitational or stronger)

3 = Natural, not forcing

3 = Invitational with 3-3 in the majors

3/ = Preempt

Preempt

Preempt is a bid in contract bridge whose primary objectives are to thwart opponents ability to bid to their best contract, with some safety, and to fully describe one's hand to one's partner in a single bid. A preemptive bid is usually made by jumping, i.e. skipping one or more bidding levels...

ive, to play

4/ = To play

In responding to the 2NT relay the opener indicates whether (s)he holds a minimum or a maximum (because of their playing strength 5-5's are generally considered maximum), and - in case of a maximum - the distribution in the majors:

3 = any minimum (responder's 3/ rebid now indicates an invite)

3 = 5-5 min or max (creates game force

Forcing bid

In the card game contract bridge, a forcing bid is any bid that obliges the partner to bid over an intermediate opposing pass. Owing to the partnership's bidding system or a bridge convention, partner must "keep the bidding open", i.e...

)

3 = 4-5 max (creates game force

Forcing bid

In the card game contract bridge, a forcing bid is any bid that obliges the partner to bid over an intermediate opposing pass. Owing to the partnership's bidding system or a bridge convention, partner must "keep the bidding open", i.e...

)

3 = 5-4 max (creates game force

Forcing bid

In the card game contract bridge, a forcing bid is any bid that obliges the partner to bid over an intermediate opposing pass. Owing to the partnership's bidding system or a bridge convention, partner must "keep the bidding open", i.e...

)

3NT = 4-4 max (creates game force

Forcing bid

In the card game contract bridge, a forcing bid is any bid that obliges the partner to bid over an intermediate opposing pass. Owing to the partnership's bidding system or a bridge convention, partner must "keep the bidding open", i.e...

)

Modifications

Variants of Ekren include the use of the 2 opening to indicate a weak hand with at least a 4-4 in the majors

Major suit

In the card game contract bridge, the major suits are spades and hearts . The major suits are of prime importance for tactics and scoring as they outrank the minor suits while bidding and also outscore them...

. This treatment has the advantage that the left hand opponent of the opener can hardly gamble on the fact that (s)he will get a second chance to bid.

Another variant that is popular in the Netherlands (where it is referred to as Tilburg Two) and Belgium is to accommodate the Ekren hands as a weak variant in the strong 2 opening. This leaves untouched the 2// openings which are commonly utilised in the Low countries

Low Countries

The Low Countries are the historical lands around the low-lying delta of the Rhine, Scheldt, and Meuse rivers, including the modern countries of Belgium, the Netherlands, Luxembourg and parts of northern France and western Germany....

 as Multi 2 diamonds

Multi 2 diamonds

Multi or Multi 2 diamonds is contract bridge convention whereby the opening bid of 2 shows multiple types of hands, which always includes a weak two bid in either major suit, while the additional meaning may be a strong balanced hand , or a 20-22 three suiter...

 and Muiderberg

Muiderberg convention

The Muiderberg convention in the card game bridge is also known as the Dutch Two opening. It is a two-level preemptive opening based on a two-suiter with precisely a five-card major and a minor suit...

(also known as Tartan or 'Jón og Símon') openings. Also, a 2 relay is now available to responder that can be used to ask for the longest (or better) of the two major suits.