A vertical tasting is conducted by tasting one wine varietal from several of vintages, yet made by the same maker. Or the tasting can be focused on the different year productions of the same varietal wine from the same producer and same vintage. This will allow you to experiment how dramatic or subtle the flavor of the wine can change from year to year.
This kind of tasting will give you a better feel to a winery’s style and composition. It will also provide a sense of the quality variations that may occur due to weather patterns, which may affect the grapes from year to year.
The tasting will usually progress from youngest to oldest wine. As the older wines tend to be more complex. It’s nice to build up to the big finale.
If you have the opportunity to take a look at the wine’s literature. The winemaker’s note might give you some more insight to other factors such as the kind of barrels they used, if they changed to new barrels, did they have trouble with insects, the kind weather they experienced. Even if you do noticed the difference, it will serve as good observations during a conversation.