The TOEFL began development in 1962 and was first administered two years later. Its purpose is to devise international students for studying in an English-speaking country or program.
Difference between iBT and PBT:
iBT
PBT
For the iBT, you will answer several questions in Reading, Listening, Speaking and Writing.
For the PBT, you will do Listening, Structure and Written Expression, Reading Comprehension and Writing.
The iBT is longer, clocking in at around 200 to 250 minutes (including one 10-minute break).
The PBT is much shorter running 140 to 150 minutes in overall length.
The TOEFL Test is now largely an iBT, though the paper-based may still be available in some areas.