Prospects of Gain
One of my quaint notions about bidding is that players bid too much in competition.
Today’s East overcalled 1. I don’t know why. His bid wasn’t obstructive or lead-directing, and his hand was too weak to expect to make much of anything.
Against 3NT, West led the ♠10, and East took the king and returned the jack. South won and had to force out both red aces to get nine winners. Assuming West had one ace, South had to dislodge it first, killing West’s entry before the defense set up the spades.

Dlr: North ♠ A 4 2
Vul: N-S Q 6 3
K J 5
♣ A 10 9 8
♠ 10 9 8 7 5 ♠ K J 3
2 A 9 8 7 4
A 10 9 4 8 7
♣ 7 5 2 ♣ Q J 4
♠ Q 6
K J 10 5
Q 6 3 2
♣ K 6 3
North East South West
1♣ 1 2NT Pass
3NT All Pass

Opening lead — ♠10

Nine Tricks

East’s overcall marked him with the A, so South led a diamond to dummy’s king at trick three and next led the jack. West won and led another spade, but South took the ace and lost a heart to the ace. Making three.
If East doesn’t overcall, North-South will bid 1♣-1, 1NT-2NT, 3NT. Then if East happens to lead a high spade, North must guess well to make his game.
Before you overcall, consider what you have to gain and lose.

Daily Question

You hold:
♠ Q 6
K J 10 5
Q 6 3 2
♣ K 6 3
Your partner opens 1♣. The next player bids 1♠. What do you say?

Your best call is a negative double, which, by agreement, shows enough strength to respond with a heart suit plus either diamonds or club support. Note that your opponent’s overcall had something to gain — it stopped you from bidding a red suit at the one level — and therefore might be justified with a lightish hand.