What kinds of English certification exams are there

There are quite a lot of English checking exams, it's not clear exactly, like IELTS, TOEFL, National English Checking and DuoYi.

IELTS is one of the most famous international standardized tests of English, established in 1989 and managed by the British Council, the University of Cambridge Examinations Board and the Australian Education International Development Agency (IDP)****. IELTS is the world's first comprehensive assessment of English language ability in four areas: listening, speaking, reading and writing. Candidates can choose between an academic test and a training test, and the test results are valid for two years.

TOEFL (full name: Test of English as a Foreign Language for non-native speakers of English) is an English language proficiency test organized by the U.S. Educational Testing Service, which is transliterated into "TOEFL" from TOEFL in Chinese.There are three types of TOEFL, namely, the paper test, the machine test, and the online test, and the full score of the new TOEFL is 120 points. TOEFL is valid for two years from the date of the test.