What is C-reactive protein, and what does its presence in the blood indicates about a person's health?

Hi doctor,

I am a 50-year-old male. Recently, I did blood work and had high C-reactive protein levels. So, I want to know what C-reactive protein (CRP) is and what its presence in the blood indicates about a person's health. How is CRP measured, and what are the normal and abnormal ranges of CRP levels in the blood? What are the common reasons for elevated CRP levels, and what health conditions or diseases are associated with increased CRP? Can CRP levels be affected by lifestyle factors, such as diet, exercise, or stress?

Thanks.