This is your South hand.
West, your left hand opponent, opens 1♣.
What is your bid if partner, North, overcalls 1♦, 1♥, 1♠, 1NT, 2♦, 2♥ or 2♠ respectively (the jump overcalls are intermediate: six-card suit, opening strength)? East passes.

Solution

Over partner's 1♦ overcall you bid 1♠. Your hand is too good to pass. Game may easily be on, for instance in spades, if partner has extra strength (he may have as much as 17 HCP) and three spades. In principle your 1♠ bid shows a five-card suit or longer.
About whether your 1♠ bid is forcing or not, opinions differ. Many partnerships play a bid in a new suit at the one or three level over partner's overcall as forcing; at the two level as not forcing (provided neither the overcaller nor the responder has jumped).
But here you couldn't care less whether 1♠ is forcing or not. Partner will only pass with minimum strength for his overcall and then game certainly is not on.

Over partner's 1♥ overcall you bid 2♥. Showing support for partner's major suit at once, is a good and practical rule, recommended by most bridge teachers. Still, not bidding such a good spade suit has its disadvantages.*
Opposite partner's simple 1♥ overcall, you are not strong enough for an invitational 3♥ bid.
(* This becomes all the more clear, when we give South ♥1062 ♦KQ7 instead of his actual ♥K106 ♦Q72. Suppose West becomes declarer after all and North leads a heart from a vulnerable holding in that suit... Therefore experts and teachers sometimes disagree about what South should do.
Teachers will mostly suggest raising hearts: 'If, having less than game-forcing values, you don't raise partner's major suit at once, but instead bid a suit of your own, there is no way you can afterwards tell partner about your fit in a non-forcing way.' A matter of simplicity in the bidding.
Experts will point out that North will lead hearts against West's contract, if South doesn't bid spades. Furthermore a spade bid may help North in evaluating the possibilities for NS.)

Over partner's 1♠ overcall you bid 3♠ (assuming you don't play this as pre-emptive, which is the modern style; those modern bidders use a 2♣ or even 3♣ cuebid here). With five-card support you will consider even 4♠, but your hand is too balanced for that. Despite the huge spade fit, there might turn out to be too many losers; partner cannot use your trumps to ruff losers. So settle for 3♠ and see whether partner has something in reserve; in that case he can bid game.

Over partner's 1NT overcall you bid 2♥, a Jacoby transfer. Over partner's 1NT overcall we bid the same as over his 1NT opening. After his (near-) compulsory 2♠ bid, you plan to jump to 3NT, giving him the choice between pass and 4♠.

Over partner's 2♦ overcall — he shows opening strength and six diamonds — you bid 2♠. Over partner's jump overcall 2♠ is forcing (see 1♦). You want to investigate which game you should be in.

Over partner's 2♥ overcall you bid 4♥. This should be a fine contract opposite opening strength and six hearts.

Over partner's 2♠ overcall you bid 4♠. What else?