Please provide a detailed response to the following question: What are the key features of a modern smartphone? Your response should contain at least 5 sentences. Highlight at least 2 sections in your answer with markdown, i.e. *highlighted section*. Include keywords *camera quality*, *battery life*, *high-speed internet*, *touchscreen display*, *operating system*. At the end of your response, please explicitly add a postscript starting with P.S.

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