What is Replication slots in PostgreSQL Streaming

What is Replication slots in PostgreSQL Streaming replication slot is active for pid production environment that unable to get around to apply There are two ERROR messages observed here 'replication slot is active for PID' replication slot postgres Active State Displays 2-33 ARP Functionality 2-33 Testing Address Resolution Replication for Recording Information 2-48 Viewing SIP

replication slot A logical replication slot is the mechanism that represents a stream of changes that can be replayed to the client in the order they were made