What is the delta in trading?

Can you explain to me what the term "delta" refers to in the context of trading? I've heard it mentioned frequently in discussions about cryptocurrency and finance, but I'm not entirely clear on its meaning or how it's used in practical applications. Is it related to the price movement of an asset? And if so, how does it help traders make informed decisions? I'd appreciate it if you could provide a clear and concise definition, along with some examples of how delta might be used in a trading strategy.