The phrase "seeing as" is used to introduce a statement that explains the reason behind another statement or situation. It functions similarly to "since" or "because" in this context.
This implies: Because it was raining, we made the decision to stay inside.
"Seeing as" serves as a conjunction to clarify the cause or basis for a particular statement or action. It helps connect explanations naturally in conversation or writing.
This explanation helps clarify how "seeing as" works in everyday English as a causal phrase linking reasons to outcomes.