diff --git a/lib/membership/email.ex b/lib/membership/email.ex
index c611742..dccec21 100644
--- a/lib/membership/email.ex
+++ b/lib/membership/email.ex
@@ -1,4 +1,37 @@
 defmodule Mv.Membership.Email do
+  @moduledoc """
+  Custom Ash type for validated email addresses.
+
+  ## Overview
+  This type extends `:string` with email-specific validation constraints.
+  It ensures that email values stored in Property resources are valid email
+  addresses according to a standard regex pattern.
+
+  ## Validation Rules
+  - Minimum length: 5 characters
+  - Maximum length: 254 characters (RFC 5321 maximum)
+  - Pattern: Standard email format (username@domain.tld)
+  - Automatic trimming of leading/trailing whitespace
+
+  ## Usage
+  This type is used in the Property union type for properties with
+  `value_type: :email` in PropertyType definitions.
+
+  ## Example
+      # In a property type definition
+      PropertyType.create!(%{
+        name: "work_email",
+        value_type: :email
+      })
+
+      # Valid values
+      "user@example.com"
+      "first.last@company.co.uk"
+
+      # Invalid values
+      "not-an-email"      # Missing @ and domain
+      "a@b"               # Too short
+  """
   @match_pattern ~S/^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}$/
   @match_regex Regex.compile!(@match_pattern)
   @min_length 5
diff --git a/lib/membership/member.ex b/lib/membership/member.ex
index d0b8124..26c876f 100644
--- a/lib/membership/member.ex
+++ b/lib/membership/member.ex
@@ -1,4 +1,36 @@
 defmodule Mv.Membership.Member do
+  @moduledoc """
+  Ash resource representing a club member.
+
+  ## Overview
+  Members are the core entity in the membership management system. Each member
+  can have:
+  - Personal information (name, email, phone, address)
+  - Optional link to a User account (1:1 relationship)
+  - Dynamic custom properties via PropertyType system
+  - Full-text searchable profile
+
+  ## Email Synchronization
+  When a member is linked to a user account, emails are automatically synchronized
+  bidirectionally. User.email is the source of truth on initial link.
+  See `Mv.EmailSync` for details.
+
+  ## Relationships
+  - `has_many :properties` - Dynamic custom fields
+  - `has_one :user` - Optional authentication account link
+
+  ## Validations
+  - Required: first_name, last_name, email
+  - Email format validation (using EctoCommons.EmailValidator)
+  - Phone number format: international format with 6-20 digits
+  - Postal code format: exactly 5 digits (German format)
+  - Date validations: birth_date and join_date not in future, exit_date after join_date
+  - Email uniqueness: prevents conflicts with unlinked users
+
+  ## Full-Text Search
+  Members have a `search_vector` attribute (tsvector) that is automatically
+  updated via database trigger. Search includes name, email, notes, and contact fields.
+  """
   use Ash.Resource,
     domain: Mv.Membership,
     data_layer: AshPostgres.DataLayer
diff --git a/lib/membership/property.ex b/lib/membership/property.ex
index de096ca..231b264 100644
--- a/lib/membership/property.ex
+++ b/lib/membership/property.ex
@@ -1,4 +1,36 @@
 defmodule Mv.Membership.Property do
+  @moduledoc """
+  Ash resource representing a custom property value for a member.
+
+  ## Overview
+  Properties implement the Entity-Attribute-Value (EAV) pattern, allowing
+  dynamic custom fields to be attached to members. Each property links a
+  member to a property type and stores the actual value.
+
+  ## Value Storage
+  Values are stored using Ash's union type with JSONB storage format:
+  ```json
+  {
+    "type": "string",
+    "value": "example"
+  }
+  ```
+
+  ## Supported Types
+  - `:string` - Text data
+  - `:integer` - Numeric data
+  - `:boolean` - True/false flags
+  - `:date` - Date values
+  - `:email` - Validated email addresses (custom type)
+
+  ## Relationships
+  - `belongs_to :member` - The member this property belongs to (CASCADE delete)
+  - `belongs_to :property_type` - The property type definition
+
+  ## Constraints
+  - Each member can have only one property per property type (unique composite index)
+  - Properties are deleted when the associated member is deleted (CASCADE)
+  """
   use Ash.Resource,
     domain: Mv.Membership,
     data_layer: AshPostgres.DataLayer
diff --git a/lib/membership/property_type.ex b/lib/membership/property_type.ex
index 7444c13..6569d1b 100644
--- a/lib/membership/property_type.ex
+++ b/lib/membership/property_type.ex
@@ -1,4 +1,48 @@
 defmodule Mv.Membership.PropertyType do
+  @moduledoc """
+  Ash resource defining the schema for custom member properties.
+
+  ## Overview
+  PropertyTypes define the "schema" for custom fields in the membership system.
+  Each PropertyType specifies the name, data type, and behavior of a custom field
+  that can be attached to members via Property resources.
+
+  ## Attributes
+  - `name` - Unique identifier for the property (e.g., "phone_mobile", "birthday")
+  - `value_type` - Data type constraint (`:string`, `:integer`, `:boolean`, `:date`, `:email`)
+  - `description` - Optional human-readable description
+  - `immutable` - If true, property values cannot be changed after creation
+  - `required` - If true, all members must have this property (future feature)
+
+  ## Supported Value Types
+  - `:string` - Text data (unlimited length)
+  - `:integer` - Numeric data (64-bit integers)
+  - `:boolean` - True/false flags
+  - `:date` - Date values (no time component)
+  - `:email` - Validated email addresses
+
+  ## Relationships
+  - `has_many :properties` - All property values of this type
+
+  ## Constraints
+  - Name must be unique across all property types
+  - Cannot delete a property type that has existing property values (RESTRICT)
+
+  ## Examples
+      # Create a new property type
+      PropertyType.create!(%{
+        name: "phone_mobile",
+        value_type: :string,
+        description: "Mobile phone number"
+      })
+
+      # Create a required property type
+      PropertyType.create!(%{
+        name: "emergency_contact",
+        value_type: :string,
+        required: true
+      })
+  """
   use Ash.Resource,
     domain: Mv.Membership,
     data_layer: AshPostgres.DataLayer