How to create a hot standby with PostgreSQL

PostgreSQL is an open source RDBMS (Relational DataBase Management System), and with any databases, the need may arise to scale and provide HA (High Availability). A single system providing a service is always a possible single point of failure – and even with virtual systems, there may be a time when you can’t add more resources to a single machine to cope with the ever-increasing load. There also may be a need to another copy of the database contents that can be queried for long-running analytics, that are not fit to be run on the highly transaction-intensive production database. This copy could be a simple restore from the most recent backup on another machine, but the data would be outdated as soon as it is restored.