Nowadays, IOT presents a lot of benefits to people and countries in many fields which in turn makes it one of the most important fields on both research and industry. Recently, NO of IOT connected things has been increased due to rapid network and communication development which in turn leads to increase amount of data exchanged especially critical data. Critical data can be military, industrial, agricultural, health and even personal data which makes IOT networks a main goal for many attacks in order to leak this critical data or even use it in order to cause catastrophic destroy for data owners.A lot of security mechanisms tried to provide a protection for both devices and things but due to devices constrained nature and IOT used protocols, a lot of them failed to provide required protection. In this paper, an introduction to IOT field, its importance and a review for IOT protocols, architectures, a lot of security and privacy challenges and a lot of solutions to that are presented.