A mammogram is an x-ray of the breast used to detect breast cancer. The document discusses the equipment used for mammography including the x-ray tube, compression device, and digital systems. It also covers positioning of the breast, types of mammograms, limitations, and various breast imaging modalities like digital mammography and breast MRI. Mammography remains the standard screening tool for breast cancer detection, though false negatives can occur and imaging is limited in women with dense breasts.