The term "multiverse" refers to the idea that there are multiple, possibly infinite, universes existing alongside our own. Each universe may have different physical laws, constants, and even dimensions. This concept arises from various fields, including cosmology, quantum mechanics, and string theory, suggesting that our universe is just one of many. In the multiverse theory, these universes can vary significantly. Some may be similar to ours, while others could be entirely different, with alternate histories or different forms of life. The multiverse concept challenges our understanding of reality and raises questions about the nature of existence itself.