The Trans-Pacific Partnership (TPP) agreement is a trade agreement between 12 countries located in the Asia-Pacific region. The countries include the United States, Canada, Japan, Australia, New Zealand, Malaysia, Vietnam, Singapore, Brunei, Peru, Mexico, and Chile.

The TPP agreement aims to create a free trade area between the participating countries, eliminating tariffs and trade barriers, and promoting economic growth, job creation, and regional integration. The agreement covers a range of areas, including trade in goods and services, intellectual property, labor rights, environmental standards, and dispute settlement mechanisms.

The TPP negotiations started in 2008 and concluded in 2015, after several rounds of talks and discussions. The agreement was signed in February 2016, but it was not ratified by all the countries involved. The United States, under the leadership of former President Donald Trump, withdrew from the agreement in 2017, citing concerns about its impact on jobs and the economy.

Despite the U.S. withdrawal, the remaining 11 countries continued to work on the agreement and signed a revised version, called the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP), in March 2018. The CPTPP includes most of the original TPP agreement, but with some changes and modifications.

The CPTPP entered into force on December 30, 2018, after six countries, including Japan and Australia, ratified it. The remaining countries are expected to follow suit in the coming months and years.

The TPP agreement and the CPTPP have been controversial in some of the participating countries, with critics arguing that they could lead to job losses, environmental degradation, and the erosion of labor rights. Supporters, on the other hand, believe that the agreements would bring economic benefits, boost trade and investment, and create new opportunities for businesses and consumers.

In conclusion, the 12 countries in the TPP agreement, now known as the CPTPP, are the United States, Canada, Japan, Australia, New Zealand, Malaysia, Vietnam, Singapore, Brunei, Peru, Mexico, and Chile. Although the United States withdrew from the agreement, the remaining 11 countries have signed a revised version of the agreement, which is expected to bring economic benefits and promote regional integration.