Mammography is a medical imaging technique that uses low-energy X-rays to examine the human breast for diagnosis and screening. The goal of mammography is the early detection of breast cancer, typically through detection of characteristic masses or abnormalities in the breast tissue. Mammograms can be used to check for breast cancer in women who have no signs or symptoms of the disease, and this type of mammogram is called a screening mammogram.

During a mammogram, the patient stands in front of a special X-ray machine, and a technologist places the breast on a plastic plate. Another plate will firmly press the breast from above, flattening it and holding it still while the X-ray is being taken. The steps are repeated to make a side view of the breast, and the other breast will be X-rayed in the same way. The electrical signals can be read on computer screens, permitting more manipulation of images to allow radiologists to view the results more clearly.

Mammography has a false-negative (missed cancer) rate of at least ten percent, partly due to dense tissue obscuring the cancer and the appearance of cancer on mammograms having a large overlap with the appearance of normal tissue. An abnormal mammogram does not always mean that there is cancer, but additional mammograms, tests, or exams may be needed before the doctor can tell for sure.

Digital mammography is a specialized form of mammography that uses digital receptors and computers instead of X-ray film to help examine breast tissue for breast cancer. Digital mammography provides electronic images of the breasts that can be enhanced by computer technology, stored on computers, and even transmitted electronically in situations where remote access to the mammogram is required. Three-dimensional (3-D) mammography, also known as digital breast tomosynthesis (DBT), is a type of digital mammography in which x-ray machines are used to take pictures of thin "slices" of the breast from different angles and computer software is used to reconstruct an image.

In summary, mammography is an X-ray imaging method used to examine the breast for the early detection of cancer and other breast diseases. It is used as both a diagnostic and screening tool, and digital mammography is a specialized form of mammography that uses digital receptors and computers instead of X-ray film to help examine breast tissue for breast cancer.