| 1950s–1960s | Symbolic AI / Expert Systems | Focused on rule-based logic and reasoning. Used for solving structured problems like math proofs and medical diagnosis. |
| 1970s–1980s | Knowledge-Based Systems | Built large databases of facts and rules. Aimed to mimic expert decision-making in narrow domains. |
| 1990s | Machine Learning (ML) | Shifted from hard-coded rules to learning from data. Enabled pattern recognition and predictive modeling. |
| 2000s | Deep Learning | Used neural networks to process unstructured data like images and speech. Revolutionized tasks like facial recognition and voice assistants. |
| 2010s | Reinforcement Learning | Focused on decision-making through trial and error. Applied in robotics, gaming (e.g., AlphaGo), and autonomous systems. |
| 2020s | Generative AI | Capable of creating original content — text, images, music — using models like GPT and DALL·E. Transformed creativity, communication, and productivity. |
| Emerging | Quantum AI | Combines quantum computing with AI to solve problems beyond classical limits. Still experimental but promising for drug discovery and cryptography. |