In military terms, a salient is a battlefield feature that projects into enemy territory. Therefore, the salient is surrounded by the enemy on three sides, making the troops occupying the salient vulnerable. The enemy's line facing a salient is referred to as a re-entrant (an angle pointing inwards). A deep salient is vulnerable to being "pinched out" across the base, forming a pocket, in which the defenders of the salient become isolated.

Salients can be formed in a number of ways. An attacker can produce a salient in the defender's line by either intentionally making a pincer movement around the flanks of a strong point, which becomes the tip of the salient, or by making a broad, frontal attack which is held up in the centre but advances on the flanks. An attacker would usually produce a salient in his own line by making a broad, frontal attack that is successful only in the centre, which becomes the tip of the salient.

In trench warfare, salients are distinctly defined by the opposing lines of trenches and they were commonly formed by the failure of a broad, frontal attack. The static nature of the trenches meant that forming a pocket was difficult but the vulnerable nature of salients meant that they were often the focus of attrition battles.

In mobile warfare, such as the German Blitzkrieg, salients were more likely to be made into pockets which became the focus of annihilation battles.

Examples of salients and pockets

• In World War I, the British occupied a large salient at Ypres for most of the war. Formed as a result of the First Battle of Ypres, it became one of the most bloody sectors of the Western Front. So enduring was the feature and so dreadful its reputation that when British infantry spoke of "The Salient", they were referring to Ypres.
• In World War I, the Germans occupied a small salient in front of Fromelles called the Sugar-loaf due to its distinctive shape. Being small it provided advantage to the occupiers by allowing them to enfilade the stretches of no man's land on either flank.
• During Operation Barbarossa, 230,000 Soviet troops were captured in a pocket at Smolensk when isolated by the Panzer forces of General Heinz Guderian on July 20, 1941.
• In World War II, the Soviet Union occupied a massive, 150 km deep, salient at Kursk that became the site of the largest tank battle in history.
• In January 1944 the Korsun Pocket was formed when the Red Army cut-off 56,000 German troops in a salient on the Dnieper River.
• In 1944, following the D-Day landings, the German Seventh Army was trapped in the Falaise pocket.
• In 1945, 325,000 German troops were isolated and captured by advancing American armies in the Ruhr pocket.
• In the Yugoslav wars the Medak Pocket was a Serb populated area in Croatia that was invaded by Croatians in September 1993.