The Anglosphere, also known as the Anglo-American world, is a Western-led sphere of influence among Anglophone countries. The core group of this sphere of influence comprises five developed countries that maintain close social, cultural, political, economic, and military ties with each other: Australia, Canada, New Zealand, the United Kingdom, and the United States. Although extended definitions do include non-Western and developing countries that were once part of the British Empire and retained English influence and common law upon independence, the Anglosphere is a distinct grouping that is not simply synonymous with countries in which the English language has official status.

Anglosphere countries are generally aligned with each other on global issues and collaborate extensively in matters of security, as exemplified by alliances like Five Eyes. The core countries of the Anglosphere are either NATO members or designated by the United States as major non-NATO allies.

The Anglosphere is the Anglo-American sphere of influence. The term was first coined by the science fiction writer Neal Stephenson in his book The Diamond Age, published in 1995. John Lloyd adopted the term in 2000 and defined it as including English-speaking countries like the United Kingdom, the United States, Canada, Australia, New Zealand, Ireland, South Africa, and the British West Indies. James C. Bennett defines anglosphere as "the English-speaking Common Law-based nations of the world", arguing that former British colonies that retained English common law and the English language have done significantly better than counterparts colonised by other European powers. The Merriam-Webster dictionary defines the Anglosphere as "the countries of the world in which the English language and cultural values predominate". Similarly, recent studies describe the Anglosphere as a non-continuous region united by the concept of a transnational imagined community, grounded in shared language, history, and cultural values. However the Anglosphere is usually not considered to include all countries where English is an official language, so it is not synonymous with anglophone.^{[better source needed]}

The definition is usually taken to include Australia, Canada, New Zealand, the United Kingdom, and the United States in a grouping of developed countries called the core Anglosphere. The term Anglosphere can also include but frequently omits Ireland and the Commonwealth Caribbean countries despite their similar domestic primacy of the English language and common law.^{[excessive citations]}

The five core countries in the Anglosphere are developed countries that maintain close cultural and diplomatic links with one another. They are aligned under such military and security programmes as:

Relations have traditionally been warm between Anglosphere countries, with bilateral partnerships such as those between Australia and New Zealand, the United States and Canada and the United States and the United Kingdom (the Special Relationship) constituting the most successful partnerships in the world.

In terms of political systems, Canada, Australia, New Zealand and the United Kingdom have Charles III as head of state, form part of the Commonwealth of Nations and use the Westminster parliamentary system of government. The United States is a presidential republic. Most of the core countries have first-past-the-post electoral systems, though Australia and New Zealand have reformed their systems and there are other systems used in some elections in the UK. As a consequence, most core Anglosphere countries have politics dominated by two major parties.

Below is a table comparing the five core countries of the Anglosphere (data for 2022/2023):