The first three Gospels (Matthew, Mark and Luke) are called the Synoptic Gospels. The term synoptic comes from the words meaning "same" (syn) and "sight" (optic), or "to see together". There is quite a bit of overlap with what these three books report, while about 90% of the Gospel of John contains different information.
There are different views on how Christians should view the overlapping information. On the one hand, if the authors are...