The OSI, or Open System Interconnection, model defines a networking framework for implementing protocols in seven layers.
The 7 layers are as follows:
Layer 1- broadcast technologies (hub, access point)
Layer 2- switch, NIC (hard coded mac address)
Layer 3- router (anything that uses Ipv4 or ipv6)
Layer 4- ports for use with applications to access the network from within an operating system, Port numbers are a way of directing packets to specific applications
Layer 5- maintains connections between hosts
Layer 6- ensures common formatting of packets so they can be recognised by any device
Layer 7- software applications e.g. web browsers