Heroes of Might and Magic has many single- and multiple-player maps you can play. There is another option for a single player, however: the campaign. The campaign is the same each time you play it, but you can play as different hero types. If you choose the Knight at the beginning, that will be your primary hero and town type throughout that same campaign. After having completed it as the Knight, you might want to play as the Warlock, and so on. Other than this, the campaigns stay exactly the same in terms of maps and such. However, where you start in each map depends on your hero type. If you are a particular hero type, you always start in the same part of the map, no matter how many times you play the campaign as that hero type.
You can choose from four different heroes: Lord Ironfist the Knight, Lord Slayer the Barbarian, Queen Lamanda the Sorceress, and Lord Alamar the Warlock. There are so many different situations during the campaign that there is no universally best choice, so it boils down to personal preference. During your adventure, you will of course capture other castles and hire heroes of different types, so you are not entirely restricted to the type you chose at the beginning. However, in each map, you will begin using the preselected hero and castle type. In each map, the castle types and locations are always the same, unlike in the regular scenarios.
The main objective of the campaign is to complete all nine maps as soon as possible; it is made somewhat easier by the fact that you only have to play eight maps, actually, but you'll find out more about that later. Unlike the regular scenarios, where you just have to defeat all your opponents, there are somewhat broader requirements to complete each map. But, again, more on that later.
Moving on now, I will provide descriptions of each map of the campaign, such as the objective, where each hero type starts, special notes and strategy and such. So as to prevent this being one great big page, I have put each of the campaign maps on their own pages, which can be accessed using the links on the left.