As an AI language model, I do not have a personal opinion, but I can provide you with information related to your question. The number of Dungeons & Dragons (D&D) books that are available in total is a bit difficult to pinpoint since the game has been constantly evolving for over 45 years. However, according to a recent count, there are over 500 official D&D books and modules published by TSR, Inc. and later by Wizards of the Coast.
The core books of D&D include the Player's Handbook, Dungeon Master's Guide, and Monster Manual. These books contain the core rules, guidelines, and creatures needed to play the game. Additionally, there are also expansion books that offer new races, classes, abilities, spells, and magic items that players can use to customize their characters. These books also usually have new monsters and adventures for game masters to use in their campaigns.
D&D also has many campaign settings, which are unique worlds with their own lore, history, and characters. These settings have their own books that contain maps, lore, and rules for playing in that world. The most famous campaign settings are Forgotten Realms, Dragonlance, Eberron, and Ravenloft.
There are also many supplemental books that offer more focused content, such as books on combat, magic, crafting, or world-building. These books are meant to enhance the core experience and provide more depth to specific game elements.
Finally, D&D has adventure modules, which are pre-written campaigns that game masters can run for their players. These modules typically include maps, encounters, NPCs, and a story for players to follow. There are hundreds of adventure modules published and cover a wide range of difficulty levels and settings.
Overall, the number of D&D books available is vast and continues to grow. With 45 years of history and a devoted fan base, D&D has become a cultural phenomenon with a seemingly endless supply of content for players and game masters alike.
