The U.S. military consists of five different branches: Army, Air Force, Coast Guard, Marine Corps, and the Navy. Generally, each of these branches is composed of active duty service members and reserve units, consisting of the Reserves and/or the National Guard. Each branch has a different mission and specialty, detailed below. Clicking on the bold name of the branch will take you to the particular branch’s website, so you can begin to get an idea of what is required for each before you make the decision to join.
There are many paths one can take to become an officer: completing an ROTC program, attending a service academy, high college or junior military college, attending a Coast Guard-specific commissioning program or commissioning with a previously earned degree.
Enlisted Soldiers also have the opportunity to become non-commissioned officers. With promotions comes the need to attend educational courses for further leadership and technical skills. Situations may arise where senior enlisted Soldiers have more experience than their immediate supervising officers. They are entrusted to mentor officers and direct junior enlisted Soldiers. In addition, enlisted soldiers with technical mastery may sign up to be complement officers. Complement officers rank higher than higher enlisted soldiers but lower than lower commissioned officers.
Tears of the sun
All active SEALs are men and members of the U.S. Navy.  [Note 1] The CIA’s highly secret and elite Special Operations Group (SOG) recruits SEAL Team operators,  with joint operations dating back to MACV-SOG during the Vietnam War .  This cooperation still exists today, as evidenced by military operations in Iraq and Afghanistan .  
The first group included Phil H. Bucklew , the “Father of Naval Special Warfare,” after whom the Naval Special Warfare Center building (Air Force Special Naval Warfare Center) is named. Commissioned in October 1942, this group entered combat in November 1942 during Operation Torch on the North African coast. Scouts and Raiders also supported landings in Sicily , Salerno , Anzio , Normandy and southern France . 
To become a Seal, there is a test in a swimming pool where recruits have to remain underwater for 20 minutes. In the first instance they are equipped with oxygen tanks for air, all they have to do is stay underwater without going up. It sounds simple enough. The catch is that they are constantly harassed by the instructors who cut the air out of their masks for painful but non-lethal periods, as well as applying other general forms of harassment, to get them to come to the surface. The recruit’s job is to not defend themselves and not panic, to hold on until the attack is over without ever leaving the water and wait for the next attack to begin.
Soldiers have 4 chances to pass this qualification test, as only one in five manages to do it on the first attempt. The main reason for suspense is panic. They are not allowed to panic.
And the reality is that studies estimate that we have mental conversations all the time in which we say 300 to 1,000 words to ourselves, every minute. Seal training makes sure that the conversation is positive as long as possible or at the very least there is no conversation. It sounds silly but it is really hard to say positive things to yourself when you are a negative person and in the midst of a crisis. Panicking about the decisive doesn’t benefit anyone, and negativity produces panic, which is precisely why the training seems to really work.
Navy SEAL , SEAL in full sea, air and land , in the U.S. Navy. A member of a special operations force trained to engage in direct raids or assaults on enemy targets, perform reconnaissance missions to report on enemy activity (especially prior to beach landings), and participate in actions against terrorist groups.
The SEALs trace their heritage to several elite units in World War II, particularly Naval Combat Demolition Units (NCDUs) and Underwater Demolition Teams (UDTs) whose “frogmen” were trained to destroy obstacles on enemy-controlled beaches prior to amphibious landings in Europe and the Pacific. Other special units of that war were scouts and raiders, who were assigned to reconnoiter coastal areas and guide landing craft to shore, and “operational swimmers” of the secret Office of Strategic Services , who are said to have pioneered modern submarine combat. During the Korean War, the UDTs carried out their usual reconnaissance and mine-clearing work, but also extended their missions beyond the beach by disrupting enemy transport lines inland.