How much can a beam hold?

Could you please elaborate on the question, 'How much can a beam hold?'" "I'm curious to understand the factors that determine the weight-bearing capacity of a beam. What kind of beam are we talking about here? Is it a wooden beam, steel beam, or some other material? Also, how is the beam supported? Are there any reinforcements or brackets involved?" "Furthermore, are there any standard testing procedures or calculations that engineers use to determine a beam's maximum load capacity? Would the length and thickness of the beam play a role in its weight-bearing capacity? Additionally, are there any safety margins or load limits that need to be considered?" "Finally, I'm also interested in knowing if the beam's weight-bearing capacity can be affected by environmental factors like temperature, humidity, or exposure to corrosive elements. Could you please provide some insights into these questions?