A vintage chart is a summary (presented as a table of ratings) of the growing conditions in various wine regions in particular years.
It is a very generalised representation of vintage quality and ratings are usually skewed in favour of what the finest producers were capable of producing in a particular region for that particular year. There are always exceptions to the rule, with certain producers performing well (or not) despite vintage conditions.
In view of this, most vintage charts should be used as a high-level guide only. Your best guide is your own palate.
The following sites offer comprehensive vintage charts for the world's wine regions: