The countries that specifically use the 18+ rating are Russia, Turkey, Maldives, Latvia, South Korea, Thailand and the United Arab Emirites.There are several other countries that have movie ratings regulating viewers under 18, though they do not use a rating specifically called 18+.
Quebec in Canada uses an 18+ rating. Latvia's 18+ rating has a blue version that means the movie is merely not recommended for minors and a red version that means the minors are prohibited from seeing the movie. Maldives has an 18+R rating that specifically restricts minors from seeing the movie in addition to their regular 18+ rating. Australia uses variations of the 18+ rating: X18+ (for high impact content) and X18+ (for sexual content). Japan also uses R18+.
Countries with other types of ratings that specifically regulate and restrict viewers under 18 in regards to certain movies include Argentina, Bulgaria, Canada, Chile, Columbia, Finland, France, Hong Kong, Hungary, Iceland, India, Ireland, Italy, Malaysia, Malta, Mexico, New Zealand, Norway, Peru, the Phillipines, Poland, Portugal, Romania, Singapore, South African countries, Spain, Switzerland, Taiwan, the United Kingdom and the United States.
An 18+ rating is usually given to films with high levels of sexual content, violence or drug-related content. Pornographic films are often given 18+ ratings.