* Defining "Hard Rock" is Subjective: What exactly constitutes "hard rock" can be debated. Bands that blend hard rock with other genres like metal, punk, or pop rock become difficult to categorize.
* Sales Data is Complex: Tracking global sales across different eras, formats (vinyl, CD, digital), and regions is a complex task. Accurate, comprehensive data isn't always available.
* Changing Popularity: Band popularity fluctuates over time. A band that dominated the 70s might not sell as much today, even with a strong legacy.
Some of the Bands Frequently Mentioned in Discussions of Top-Selling Hard Rock:
* Led Zeppelin: One of the best-selling rock bands of all time, with a huge global impact.
* AC/DC: Known for their high-energy, classic hard rock sound and massive global fanbase.
* Guns N' Roses: One of the most successful rock bands of the 1980s and 90s, with iconic albums like "Appetite for Destruction."
* Van Halen: A highly influential hard rock band with a distinctive sound and popular albums like "1984."
* Queen: While known for their flamboyant rock opera style, they often get included in discussions of hard rock giants.
Ultimately, it's hard to crown a definitive "number 1." It depends on your definition of "hard rock" and what metric you prioritize (album sales, singles sales, digital downloads, etc.).