The evolution of Artificial Intelligence (AI) has progressed into a dynamic new phase with the emergence of \textbf{multimodal AI}—systems capable of comprehending and synthesizing information from diverse input sources, including text, images, audio, video, and sensor data. Unlike unimodal AI models restricted to a single data type, multimodal AI reflects a more holistic, human-like understanding by integrating various modalities to form richer contextual interpretations and enable more intuitive responses. This paper traces the historical development of multimodal AI, from early modality fusion techniques to the latest transformer-based architectures such as CLIP, DALL·E, Flamingo, Gemini, and GPT-4o. It examines the technological underpinnings that enable cross-modal alignment, embedding, and reasoning, highlighting how these architectures achieve semantic coherence across diverse inputs. Multimodal AI is revolutionizing sectors such as healthcare, autonomous robotics, entertainment, education, and accessibility. Applications range from real-time medical diagnostics and AIpowered content generation to emotionally responsive virtual assistants and intelligent surveillance systems. Despite its rapid advancement, the field faces substantial challenges— including data alignment complexities, model interpretability, ethical concerns, and computational scalability. By enabling machines to perceive and process the world in a manner more aligned with human cognition, multimodal AI is closing the gap between artificial perception and human experience. This article explores not only its transformative capabilities but also the future frontiers of multimodal intelligence, where AI systems can reason, empathize, and interact with unprecedented depth and nuance, thus redefining the landscape of human-computer interaction and intelligent systems design.