What the "F" is vintage?
Vintage is one of those things you just have to know about wine. How much you should know about wine vintages all depends on how seriously you want to take your wine.
What is vintage in relation to wine?
Simply put, vintage is the year in which a wine is grown, harvested, and turned into juice. Vintage can be a great way to judge the quality of wine, especially for wines at the upper end of the price scale or for small wineries. What makes a vintage good or bad is depends on the role that nature played in the growing of the grapes that year, and whether or not nature decided to be good or bad to the farmers.
Does a wine's vintage matter?
Whether or not a wine's vintage matters depends on how serious the wine is, and how serious you take your wine. Most wines that we buy off the shelves aim for consistency from year to year, and have methods to make a wine you will recognize from one year to the next. Regions like Bordeaux, and Rioja on the other hand take vintages exceptionally seriously going so far as to collectively declare what was a good year and a not so good year. For example a Gran Reserva Rioja can only come from years that are collectively decided to be exceptional vintages.
If you take wine seriously, then vintages are crucial in understanding what a good wine is. You will need to carry with you a wealth of information such as summer temperatures in California, or rainfall in Bordeaux to be able to predict it. Or you could just keep a list of what years are good in what regions.
What makes a vintage good, or exceptional?
At the end of the day wine vintages come down to weather. Here is a simple list of how the break down.
Good Vintage - Everything was balanced. There was neither too much rain nor too little, and the climate was pretty good for the grapes to grow.
Bad Vintage - Thins were either scarce or came in excess. Too much or too little rain really stressed out the grapes. Might also include some exceptional weather phenomenons like hail storms or (sadly) wildfire.
Exceptional Vintage - Everything was ideal, nothing went wrong, and the gods seemed to smile on the humble folks working the fields.