Signs and symptoms
By far the most common hernias develop in the  abdomen when a weakness in the abdominal wall evolves into a localized hole, or "defect", through which adipose tissue, or abdominal organs covered with peritoneum, may protrude. Another common hernia involves the spinal discs and causes sciatica. A hiatus hernia occurs when the stomach protrudes into the mediastinum through the esophageal opening in the diaphragm. Hernias may or may not present with either pain at the site, a visible or palpable lump, or in some cases more vague symptoms resulting from pressure on an organ that has become "stuck" in the hernia, sometimes leading to organ dysfunction. Fatty tissue usually enters a hernia first, but it may be followed or accompanied by an organ. Hernias are caused by a disruption or opening in the fascia, or fibrous tissue, which forms the abdominal wall. It is possible for the bulge associated with a hernia to come and go, but the defect in the tissue will persist. Symptoms and signs vary depending on the type of hernia. Symptoms may or may not be present in some inguinal hernias. In the case of reducible hernias, a bulge in the groin or in another abdominal area can often be seen and felt. When standing, such a bulge becomes more obvious.
Double indirect hernia: an indirect inguinal hernia with two hernia sacs, without a concomitant direct hernia component (as seen in a pantaloon hernia). Hiatus hernia: a hernia due to "short oesophagus" — insufficient elongation — stomach is displaced into the thorax
Littres hernia: a hernia involving a Meckels diverticulum. It is named after the French anatomist Alexis Littré (1658–1726). Lumbar hernia: a hernia in the lumbar region (not to be confused with a lumbar disc hernia), contains the following entities:
Petits hernia: a hernia through Petits triangle (inferior lumbar triangle). It is named after French surgeon  Jean Louis Petit (1674–1750). Grynfeltts hernia: a hernia through Grynfeltt-Lesshaft triangle (superior lumbar triangle). It is named after physician Joseph Grynfeltt (1840–1913). Maydls hernia: two adjacent loops of small intestine are within a hernial sac with a tight neck. The intervening portion of bowel within the abdomen is deprived of its blood supply and eventually becomes necrotic. Obturator hernia: hernia through obturator canal
Parastomal hernias, which is when tissue protrudes adjacent to a stoma tract. Paraumbilical hernia: a type of umbilical hernia occurring in adults
Perineal hernia: a perineal hernia protrudes through the muscles and fascia of the perineal floor. It may be primary but usually is acquired following perineal prostatectomy, abdominoperineal resection of the rectum, or pelvic exenteration. Properitoneal hernia: rare hernia located directly above the peritoneum, for example, when part of inguinal hernia projects from the deep inguinal ring to the preperitoneal space.