Picture jumps are used in the 2/1 bidding system.
Alternatively you can watch a picture jumps video instead.
If we start with an auction, with no intervening bidding such as:-
- 1♠-2♣
- 2♥ -?
So here we can bid 2♠ / 3♠ / 4♠ to show different kinds of holdings.
Firstly 2♠
A hand such as:
- ♠ K107
- ♥ K5
- ♦ K76
- ♣ KJ973
The two spade bid shows 3 card spade support but also denies holding a good 5 card club suit and good spades now making slam less likely.
Secondly 3♠
A hand such as:
- ♠ KQ7
- ♥ A5
- ♦ 876
- ♣ AKJxx
This raise shows good trump support, a good club suit and an outside control in one of the red suits.
And Finally 4♠
A hand such as:
- ♠ KQ7
- ♥ 65
- ♦ J76
- ♣ AKJxx
This shows excellent trump support and a great club support but no controls in the other suits.
By having all these different bids set in stone opener is more likely to know whether to go for a slam or not.