From Wikipedia:
In the medieval constitution of a city, a citizen was a full member of the community who enjoyed all rights and duties. The other inhabitants of the village were called Inwohner or sojourners . In the early Middle Ages, initially only members of the urban upper class who came from families capable of advising them had civil rights. Later, the citizenship expanded until residents without real estate were increasingly able to obtain citizenship or beisassen were granted their own “beisassen rights”, which differed only slightly from the rights of citizens.
The most important and at least in the early and high Middle Ages indispensable prerequisite for citizenship was real estate property ownership, more precisely the ownership of a tax property subject to within the municipality or city. Owners of small houses that were built on the land of the citizens were initially from citizenship excluded . The number of citizens was comparatively small compared to the number of residents. Other prerequisites were an honest birth, that is, that one had to be born in wedlock and that one did not come from an executioner, grave digger or other “dishonest” professions , a minimum wealth and the fact that one was not involved in legal disputes at the time of admission.
The title of citizen, in old records such as matriculation often called the Latin civis , was not a title that one inherited or received for life. Rather, it had to be applied for and was granted if the relevant requirements were met. This inclusion in the citizenship was documented in the so-called citizenship role , whereby a corresponding fee , the “citizenship money”, [12] was due. This citizen's money could also be deferred - a measure that cities took when they wanted to recruit new residents. The admission only became legally binding with the participation of the new citizen in the general oath , which was usually taken by the entire citizenry when a newly formed city council met.
If the requirement no longer applies, in particular the sale or handover of the house, which established citizenship, the citizenship lapsed again and the citizen returned to the status of a resident.
So if the son of an arable citizen took over his father's property, he could apply for citizenship, which his father lost. Many craftsmen without a successor within the family leased their business to a resident, but remained citizens as owners. Often they later sold the property to the lessee , granting them a right of residence. This reversed the status: the new owner received civil rights, the old one lived as a resident on the property.
Admission to the citizenship was accompanied by various obligations that did not affect the residents or affected them to a lesser extent. They included various taxes, guard and military service, compulsory work in public construction work, and binding to the municipal jurisdiction. In addition to political participation, which is often graded according to income, and freedom from landlords, civil rights also included other privileges. The city guaranteed the legal protection of the citizen against external claims, for example against creditors, bought citizens out of captivity or led for their citizens feuds .