Transport layer is responsible for

• multiplexing and demultiplexing traffic
• establishing long running connections
• ensuring data integrity through error checking and data verification

Multiplexing: node on a network’s ability to direct traffic toward many different receiving service.

Demultiplexing: same but on receiving end towards the proper receiving service

Port: A 16-bit number that’s used to direct traffic to specific services running on a networked computer

Different network services run while listening on specific ports for incoming requests

commonly know ports:

• http: 80
• ftp: 21

Full IP and ports ex.

• 10.1.1.100:80

when written this way it’s known as socket address or socket number

Same device might also be running an FTP or file transfer protocol server. FTP is an older method used for transferring files from one computer to another, but still in use today.