# Address Book Overview
The **Address Book** is the central hub for managing companies, departments, and individuals within Dewesoft CRM. It forms the foundation of your CRM data, enabling a clear and hierarchical view of your business relationships.
This chapter outlines how the four key entity types — **Accounts**, **Child Accounts**, **Departments**, and **Contacts** — relate to each other and how they form a structured, visual **account family tree**.
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#### **Account**
An **Account** represents a **legal business entity** registered in a national company register.
**Key Attributes:**
- **Legal Company Name**
- **Tax Number**
- **Billing Address**
Accounts are the top-level entities in your CRM. They may have related child entities (Child Accounts, Departments, Contacts), but they themselves are standalone representations of registered companies.
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#### **Child Account**
A **Child Account** is functionally identical to a standard Account, with the same legal attributes. The distinction lies in its relationship.
When is an Account a Child Account?
- When it is **linked as a child** to another Account.
Typical use cases for Child Account(s):
- A **subsidiary**
- A **spin-off company**
- A **branch office** within a larger account group with its own registered legal entity, billing address, and TAX number
This relationship enables **grouping multiple legal entities** under one parent, helping you track corporate structures and related business units.
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#### **Department**
A **Department** is a **subdivision within an Account** (or Child Account). It does *not* exist independently and always inherits from a parent Account.
**Use Cases:**
- Internal teams such as:
- *NVH Testing Department*
- *Quality Control*
- *Durability Lab*
- *Etc.*
- Different **physical locations** under the same legal company
- e.g., “Volkswagen Testing Center – Munich Branch”
**Key Department Rules:**
- Every Department **must belong to an Account or Child Account**
- Departments are used to **group opportunities, activities, and contacts** at a finer level
- A Department is **not a legal entity**, but a logical grouping mechanism
- You cannot set the billing address to a department, as it inherits one from its parent Account. If you need to change the billing address of a Department, you are probably working with a different Account. In this case, it's better to open a separate account and link it to your parent Account as a Child Account.
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#### **Contact**
A **Contact** is a **real individual** that you interact with. The contact will be uniquely identified by **Email address**.
**Relationship Rules:**
- A Contact may:
- Belong to **an Account only.**
- Belong to **a Department**, in which case it also **automatically belongs to the parent Account.**
- Contacts can be linked to **multiple Departments** within the same or related Accounts.
This flexibility allows you to accurately model the real-world scenario of professionals who:
- Operate across multiple teams or departments
- Are involved in several roles within a business relationship
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#### **Account Family Tree**
The CRM’s **Account Family Tree** visually represents hierarchical relationships between:
- Accounts and Child Accounts
- Departments
- Contacts
This structure allows you to:
- **Easily navigate** complex corporate hierarchies
- **Group related entities** under a unified umbrella
- **Improve visibility** into how different parts of an organization interact with Dewesoft
> 💡 *You can view the Account Family Tree in the CRM to understand all relationships at a glance.* A diagram will be provided in this manual to illustrate typical tree structures and linking best practices.