The permanent residence in Germany allows the people to live and work in the country. Getting a permanent residence does not mean that people have got the German citizenship. But people can enjoy more benefits in comparison to the immigrants with temporary resident permits.
People coming from EEA or EU do not have to apply for this permit. It is so because Germany has already permitted them to live and work in the country. People of EU or EEA also have the option to EC long-term residence permit.
The citizens of the UK and other non-EU or non-EEA countries can apply for the residence permit after they have spent five years in the country. There are some situations in which candidates are allowed to apply for the permit after completing two years in Germany. This option is available for those people who have studied in Germany and continued to work in the country for more than two years.
Individuals can also apply for a permit for permanent residence if they are married to German citizens.