Ranks and insignia of NATO are combined military insignia used by the member countries of the North Atlantic Treaty Organization.
The rank scale is used for specifying posts within NATO.

Definitions

NATO maintains a "standard rank scale" in an attempt to match every member country's military rank to corresponding ranks used by the other members. The rank categories were established in the document STANAG

STANAG

STANAG is the NATO abbreviation for Standardization Agreement, which sets up processes, procedures, terms, and conditions for common military or technical procedures or equipment between the member countries of the alliance. Each NATO state ratifies a STANAG and implements it within their own...

 2116, formally titled NATO Codes for Grades of Military Personnel. There are two scales, though not all member countries use all the points on the NATO scales and some have more than one rank at some points:

Officer ranks

• OF1–OF10 (bottom to top) are used for officers

Other ranks

• OR1–OR9 (bottom to top) are used for other ranks
  Other Ranks
  Other Ranks in the British Army, Royal Marines and Royal Air Force are those personnel who are not commissioned officers. In the Royal Navy, these personnel are called ratings...
  
  

Warrant officers

• WO1-WO5 (bottom to top) are used for United States warrant officer
  Warrant Officer
  A warrant officer is an officer in a military organization who is designated an officer by a warrant, as distinguished from a commissioned officer who is designated an officer by a commission, or from non-commissioned officer who is designated an officer by virtue of seniority.The rank was first...
  
  s only.

Other countries use only regular officer ranks, do not have warrant officers, or warrant officers are considered as Other or Enlisted Rank).

Army

• Ranks and insignia of NATO Armies Officers
  Ranks and insignia of NATO armies officers
  Rank comparison chart of all armies of NATO member states.- Officers :- Warrant officers :Warrant officers rank below officers and above enlisted servicemen....
  
  
• Ranks and insignia of NATO Armies Enlisted
  Ranks and insignia of NATO Armies Enlisted
  The following lists the enlisted ranks and insignia of NATO member armies:-Other/Enlisted ranks :-See also:* NATO* Ranks and insignia of NATO* Ranks and insignia of NATO Armies Officers* Ranks and insignia of NATO Armies Enlisted...
  
  

Air Force

• Ranks and insignia of NATO Air Forces Officers
  Ranks and insignia of NATO Air Forces Officers
  -Officers :* 1 Honorary/War time rank.* 2 The higher stripe of the rank has a red outline.Note that the NATO officer rank codes are differently numbered from the US officer rank codes .-See also:...
  
  
• Ranks and insignia of NATO Air Forces Enlisted
  Ranks and insignia of NATO Air Forces Enlisted
  The following are the ranks and insignia of NATO Air Forces Enlisted personnel for each member nation.- Other Ranks :- See also :* NATO* Ranks and insignia of NATO* Ranks and insignia of NATO Armies Officers...
  
  

Navy

• Ranks and insignia of NATO Navies Officers
  Ranks and insignia of NATO Navies Officers
  -Officers :* 1 Honorary or wartime rank.* 2 Reserved for the monarch.* 3 The higher star of the rank has a red enamel.-See also:* Ranks and insignia of NATO* Ranks and insignia of NATO Armies Officers* Ranks and insignia of NATO Armies Enlisted...
  
  
• Ranks and insignia of NATO Navies Enlisted
  Ranks and insignia of NATO Navies Enlisted
  -Other Ranks :-See also:* NATO* Ranks and insignia of NATO* Ranks and insignia of NATO Armies Officers* Ranks and insignia of NATO Armies Enlisted* Ranks and insignia of NATO Air Forces Officers* Ranks and insignia of NATO Air Forces Enlisted...