Some information such as salesperson code, territory code, country code, language code, address details and communication details for contacts are same as the company the contacts are attached to. To save you from data entry work, this information can be inherited from Companies to Contacts. You can define what information to be inherited and what information not to be inherited at the Inheritance tab in Relationship Managment Setup Form. Please note that Relation Management Setup is accessed from the Sales & Marketing --> Setup --> Marketing Setup
Navision will copy the information to Contact Card when the contact is first created for the company. Later, when you change the information in the company, the information in the contacts will also get updated accordingly.
Besides using Inheritance, you can also setup Default value to be used while creating a new contact. But, Please note that the Inheritance value will overrides Default values.