IF you are new to competitive bridge, you may have noticed two blue cards in the front section of your bidding box. While you would do well to ignore the Dark Blue Card (redouble—for a cautionary tale about this card see here), proper use of the Light Blue Card is essential to keep opponents happy and to stop them using their Orange Card (calling the Tournament Director).
You've probably seen people using the Light Blue Card already. It says "ALERT" on it, and you show this to opponents to warn them that a bid (or pass, or double) means something they might not be expecting. They will often then ask you what the bid means—but they are entitled to ask whether or not there is an ALERT.
Here are the three most important principles for using the ALERT card:
Unfortunately, the ALERT card isn't the only way to warn opponents about a call. Somtimes you are supposed to ANNOUNCE it instead, by saying a set phrase. This only occurs in a handful of situations, generally because there are two common meanings which are different enough that you need to warn opponents, but neither of which is unusual enough for the ALERT card.
Here is a full list of times you might need to announce:
Do not make the mistake of confusing similar situations with these—these are the only times you should ANNOUNCE. Do not try to announce weak jump overcalls, responses to 2NT, responses to a 1NT overcall, transfers to the minors, etc.
So, that's announcing. Apart from these situations, you should generally alert all conventional bids at the 1-, 2-, or 3-level. However, you should not alert if the bid is at the 4-level or higher. This means that you do not alert Blackwood!
Doubles are a little more complicated—and in my opinion the regulations for doubles are terrible. In general, you should alert a double if it is not for takeout. So you should alert penalty doubles! This may seem crazy, but there are three exceptions:
You probably don't need to worry about exceptions to these rules, or alerting passes or redoubles. I wrote an earlier article when the regulations changed last year, which goes into more detail.
Also, don't worry if you—or your partner—get these wrong, as long as you try to get them right! Just enjoy your matches, and don't be afraid to ask opponents about their alerted bids!