How to identify steel I-beams?

Could you please elaborate on the process of identifying steel I-beams? What are the key characteristics or features that distinguish them from other types of beams? Is there a specific method or technique that professionals use to accurately identify steel I-beams? Additionally, could you provide any guidelines or tips on how to assess the quality or condition of these beams? It would be helpful to understand the overall process from start to finish, including any tools or equipment required for identification.