How much nicotine is in a cigarette?

I'm curious about the nicotine content in a cigarette. Could you provide a brief overview of the typical nicotine levels found in a standard cigarette? I understand that nicotine levels can vary depending on factors like the type of tobacco, the manufacturing process, and the brand, but I'm interested in a general estimate. Is there a standard range or an average amount that one can expect to find in a cigarette? And how does nicotine affect the body and health in the long term? It's important to have a clear understanding of these factors in order to make informed decisions about smoking habits.