Virtually the database migration can happen from any other relational database system to PostgreSQL. Due to the flexibility of the solution the target database can be any other relational database systems like Microsoft SQL, MySQL, Oracle, DB2. The source database is extracted into an XML structure, so this creates a very powerful and adaptable mechanism for data migration.
PostgreSQL is called very often simply Postgres. It is an object-relational database management system (ORDBMS) available for Linux, FreeBSD, Solaris, Mac OS X, Windows etc.