TOEFL

Usually, the Official Guide by ETS and Kaplan TOEFL Prep have the best reviews online. Students like them because they are clear, updated, and close to the real test. 

If your English is already good and you want a high score. Try Delta's Key to the TOEFL iBT: This is more advanced and detailed. The Collins TOEFL books are also good for improving speaking, listening, etc.

Barron's Essential Words for the TOEFL (7th edition) is good for TOEFL vocabulary. It is made only for TOEFL vocab.

One can check the TOEFL prepration books, which is best for practice: 

• Barron's TOEFL iBT has around 7 full tests
• Kaplan and the Official Guide have around 4 practice tests each

The best book for real TOEFL questions is the Official Guide by ETS, because ETS makes the real exam.

Yes, TOEFL iBT is accepted worldwide for bachelor's, master's, MBA, and PhD programs. Just make sure the test is taken at an approved center.

For PhD programs, TOEFL score usually needs to be above 90, and many top universities want 100 or more. Some programs also look at writing and speaking scores carefully.

Most MBA programs ask for TOEFL iBT 90 to 105. Top B-schools like Harvard, Wharton, INSEAD ask for 100 or higher.

The TOEFL cut-off is usually 80 to 100. Courses like MBA, Computer Science, Law, or Engineering may need 95 to 105+.

For most bachelor's (undergraduate) programs, universities ask for TOEFL iBT score between 70 to 90. Top universities may want 90 or above, and some may ask for minimum section scores too.