diff --git a/src/api/invoice.rs b/src/api/invoice.rs
index 74e7844..611a5a6 100644
--- a/src/api/invoice.rs
+++ b/src/api/invoice.rs
@@ -27,10 +27,12 @@ use crate::{
 /// For example, the next invoice number after `INVOICE-1234` is `INVOICE-1235`.
 #[derive(Debug, Default, Clone)]
 pub struct GenerateInvoiceNumber {
+    /// The invoice number. If you omit this value, the default is the auto-incremented number from the last number.
     pub invoice_number: Option<InvoiceNumber>,
 }
 
 impl GenerateInvoiceNumber {
+    /// New constructor.
     pub fn new(invoice_number: Option<InvoiceNumber>) -> Self {
         Self { invoice_number }
     }
@@ -60,10 +62,12 @@ impl Endpoint for GenerateInvoiceNumber {
 /// Include invoice details including merchant information. The invoice object must include an items array.
 #[derive(Debug, Clone)]
 pub struct CreateDraftInvoice {
+    /// The invoice details.
     pub invoice: InvoicePayload,
 }
 
 impl CreateDraftInvoice {
+    /// New constructor.
     pub fn new(invoice: InvoicePayload) -> Self {
         Self { invoice }
     }
@@ -89,13 +93,15 @@ impl Endpoint for CreateDraftInvoice {
     }
 }
 
-/// Get an invoice by ID.
+/// Shows details for an invoice, by ID.
 #[derive(Debug, Clone)]
 pub struct GetInvoice {
+    /// The invoice id.
     pub invoice_id: String,
 }
 
 impl GetInvoice {
+    /// New constructor.
     pub fn new(invoice_id: String) -> Self {
         Self { invoice_id }
     }
@@ -117,14 +123,16 @@ impl Endpoint for GetInvoice {
     }
 }
 
-/// List invoices
+/// Lists invoices. To filter the invoices that appear in the response, you can specify one or more optional query parameters.
 /// Page size has the following limits: [1, 100].
 #[derive(Debug, Clone)]
 pub struct ListInvoices {
+    /// The endpoint query.
     pub query: Query,
 }
 
 impl ListInvoices {
+    /// New constructor.
     pub fn new(query: Query) -> Self {
         Self { query }
     }
@@ -150,13 +158,19 @@ impl Endpoint for ListInvoices {
     }
 }
 
-/// Delete an invoice
+/// Deletes a draft or scheduled invoice, by ID. Deletes invoices in the draft or scheduled state only. 
+/// 
+/// For invoices that have already been sent, you can cancel the invoice. 
+/// 
+/// After you delete a draft or scheduled invoice, you can no longer use it or show its details. However, you can reuse its invoice number.
 #[derive(Debug, Clone)]
 pub struct DeleteInvoice {
+    /// The invocie id.
     pub invoice_id: String,
 }
 
 impl DeleteInvoice {
+    /// New constructor.
     pub fn new(invoice_id: String) -> Self {
         Self { invoice_id }
     }
@@ -178,9 +192,12 @@ impl Endpoint for DeleteInvoice {
     }
 }
 
+/// The update invoice query.
 #[derive(Debug, Clone, Serialize, Builder)]
 pub struct UpdateInvoiceQuery {
+    /// Indicates whether to send the invoice update notification to the recipient.
     pub send_to_recipient: bool,
+    /// Indicates whether to send the invoice update notification to the merchant.
     pub send_to_invoicer: bool,
 }
 
@@ -189,11 +206,14 @@ pub struct UpdateInvoiceQuery {
 /// Fully updates an invoice, by ID. In the JSON request body, include a complete invoice object. This call does not support partial updates.
 #[derive(Debug, Clone)]
 pub struct UpdateInvoice {
+    /// The updated invoice object.
     pub invoice: Invoice,
+    /// The update invoice query.
     pub query: UpdateInvoiceQuery,
 }
 
 impl UpdateInvoice {
+    /// New constructor.
     pub fn new(invoice: Invoice, query: UpdateInvoiceQuery) -> Self {
         Self {
             invoice,
@@ -226,14 +246,17 @@ impl Endpoint for UpdateInvoice {
     }
 }
 
-/// Cancel an invoice.
+/// Cancels a sent invoice, by ID, and, optionally, sends a notification about the cancellation to the payer, merchant, and CC: emails.
 #[derive(Debug, Clone)]
 pub struct CancelInvoice {
+    /// The invoice id.
     pub invoice_id: String,
+    /// The reason of the cancelation.
     pub reason: CancelReason
 }
 
 impl CancelInvoice {
+    /// New constructor.
     pub fn new(invoice_id: String, reason: CancelReason) -> Self {
         Self {
             invoice_id,
diff --git a/src/api/mod.rs b/src/api/mod.rs
index bc9b094..778d0a3 100644
--- a/src/api/mod.rs
+++ b/src/api/mod.rs
@@ -1,2 +1,4 @@
+//! This module contains the api endpoints.
+
 pub mod orders;
 pub mod invoice;
\ No newline at end of file
diff --git a/src/api/orders.rs b/src/api/orders.rs
index f73ded3..ece2ee6 100644
--- a/src/api/orders.rs
+++ b/src/api/orders.rs
@@ -4,17 +4,24 @@
 
 use std::borrow::Cow;
 
+use derive_builder::Builder;
+use serde::Serialize;
+use serde_json::json;
+
 use crate::{
     data::orders::{Order, OrderPayload, PaymentSourceResponse},
     endpoint::Endpoint,
 };
 
+/// Creates an order.
 #[derive(Debug)]
 pub struct CreateOrder {
-    order: OrderPayload,
+    /// The order payload.
+    pub order: OrderPayload,
 }
 
 impl CreateOrder {
+    /// New constructor.
     pub fn new(order: OrderPayload) -> Self {
         Self { order }
     }
@@ -42,12 +49,15 @@ impl Endpoint for CreateOrder {
 
 // TODO: Update order.
 
+/// Query an order by id.
 #[derive(Debug)]
 pub struct ShowOrderDetails {
-    order_id: String,
+    /// The order id.
+    pub order_id: String,
 }
 
 impl ShowOrderDetails {
+    /// New constructor.
     pub fn new(order_id: &str) -> Self {
         Self {
             order_id: order_id.to_string(),
@@ -71,16 +81,48 @@ impl Endpoint for ShowOrderDetails {
     }
 }
 
-#[derive(Debug)]
+/// The payment source used to fund the payment.
+#[derive(Debug, Serialize, Builder, Clone)]
+pub struct PaymentSourceToken {
+    /// The PayPal-generated ID for the token.
+    pub id: String,
+    /// The tokenization method that generated the ID.
+    /// 
+    /// Can only be BILLING_AGREEMENT.
+    pub r#type: String,
+}
+
+/// Payment source used in the capture order endpoint.
+#[derive(Debug, Serialize, Builder, Clone)]
+pub struct PaymentSource {
+    /// The tokenized payment source to fund a payment.
+    pub token: PaymentSourceToken,
+}
+
+/// The capture order endpoint body.
+#[derive(Debug, Serialize, Clone)]
+pub struct PaymentSourceBody {
+    /// The payment source definition.
+    pub payment_source: PaymentSource,
+}
+
+/// Captures payment for an order. To successfully capture payment for an order, 
+/// the buyer must first approve the order or a valid payment_source must be provided in the request. 
+/// A buyer can approve the order upon being redirected to the rel:approve URL that was returned in the HATEOAS links in the create order response.
+#[derive(Debug, Clone, Builder)]
 pub struct CaptureOrder {
-    order_id: String,
-    // TODO: payment source? https://developer.paypal.com/docs/api/orders/v2/#orders_capture
+    /// The id of the order.
+    pub order_id: String,
+    /// The endpoint body.
+    pub body: Option<PaymentSourceBody>
 }
 
 impl CaptureOrder {
+    /// New constructor.
     pub fn new(order_id: &str) -> Self {
         Self {
             order_id: order_id.to_string(),
+            body: None,
         }
     }
 }
@@ -88,7 +130,7 @@ impl CaptureOrder {
 impl Endpoint for CaptureOrder {
     type Query = ();
 
-    type Body = ();
+    type Body = PaymentSourceBody;
 
     type Response = Order;
 
@@ -99,18 +141,29 @@ impl Endpoint for CaptureOrder {
     fn method(&self) -> reqwest::Method {
         reqwest::Method::POST
     }
+
+    fn body(&self) -> Option<&Self::Body> {
+        self.body.as_ref()
+    }
 }
 
+/// Authorizes payment for an order. To successfully authorize payment for an order, 
+/// the buyer must first approve the order or a valid payment_source must be provided in the request. 
+/// A buyer can approve the order upon being redirected to the rel:approve URL that was returned in the HATEOAS links in the create order response.
 #[derive(Debug)]
 pub struct AuthorizeOrder {
+    /// The order id.
     order_id: String,
-    // TODO: payment source? https://developer.paypal.com/docs/api/orders/v2/#orders_authorize
+    /// The endpoint body.
+    pub body: Option<PaymentSourceBody>
 }
 
 impl AuthorizeOrder {
+    /// New constructor.
     pub fn new(order_id: &str) -> Self {
         Self {
             order_id: order_id.to_string(),
+            body: None,
         }
     }
 }
@@ -118,7 +171,7 @@ impl AuthorizeOrder {
 impl Endpoint for AuthorizeOrder {
     type Query = ();
 
-    type Body = ();
+    type Body = PaymentSourceBody;
 
     type Response = Order;
 
@@ -129,6 +182,10 @@ impl Endpoint for AuthorizeOrder {
     fn method(&self) -> reqwest::Method {
         reqwest::Method::POST
     }
+
+    fn body(&self) -> Option<&Self::Body> {
+        self.body.as_ref()
+    }
 }
 
 #[cfg(test)]
diff --git a/src/client.rs b/src/client.rs
index 7331a93..97abf72 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -1,3 +1,5 @@
+//! The paypal api wrapper client, which holds the http request client.
+
 use reqwest::header::{self, HeaderMap};
 use serde::Deserialize;
 use std::time::Duration;
@@ -186,6 +188,7 @@ impl Client {
         }
     }
 
+    /// Executes the given endpoint with the given headers.
     pub async fn execute_ext<E>(&self, endpoint: E, headers: HeaderParams) -> Result<E::Response, ResponseError>
     where
         E: Endpoint,
@@ -214,6 +217,9 @@ impl Client {
         }
     }
 
+    /// Executes the given endpoints with the default headers.
+    /// 
+    /// You must remember to call `get_access_token` first or this may fail due to not being authed.
     pub async fn execute<E>(&self, endpoint: E) -> Result<E::Response, ResponseError>
     where
         E: Endpoint,
diff --git a/src/data/invoice.rs b/src/data/invoice.rs
index 8d6e240..e58992e 100644
--- a/src/data/invoice.rs
+++ b/src/data/invoice.rs
@@ -1,3 +1,5 @@
+//! Paypal object definitions used in the invoice api.
+
 use crate::{data::common::*, data::common::LinkDescription};
 use derive_builder::Builder;
 use serde::{Deserialize, Serialize};
diff --git a/src/data/mod.rs b/src/data/mod.rs
index cab894e..ecc762c 100644
--- a/src/data/mod.rs
+++ b/src/data/mod.rs
@@ -1,3 +1,5 @@
+//! This module contains the data structures used in the api endpoints.
+
 pub mod common;
 pub mod orders;
 pub mod invoice;
\ No newline at end of file
diff --git a/src/data/orders.rs b/src/data/orders.rs
index efdb0cd..0beb13a 100644
--- a/src/data/orders.rs
+++ b/src/data/orders.rs
@@ -1,3 +1,5 @@
+//! Paypal object definitions used by the orders api.
+
 use super::common::*;
 use crate::errors::{PaypalError, ResponseError};
 use crate::HeaderParams;
@@ -719,7 +721,9 @@ pub struct Order {
     pub links: Vec<LinkDescription>,
 }
 
+/// An invoice number.
 #[derive(Debug, Serialize, Deserialize, Clone)]
 pub struct InvoiceNumber {
+    /// The invoice number.
     pub invoice_number: String,
 }
\ No newline at end of file
diff --git a/src/endpoint.rs b/src/endpoint.rs
index d152045..4600678 100644
--- a/src/endpoint.rs
+++ b/src/endpoint.rs
@@ -1,26 +1,37 @@
+//! This module contains the endpoint trait used to implemented api endpoints.
+
 use std::borrow::Cow;
 use serde::{Serialize, de::DeserializeOwned};
 use crate::{SANDBOX_ENDPOINT, LIVE_ENDPOINT};
 
+/// A trait implemented by api endpoints.
 pub trait Endpoint {
+    /// The serializable query type.
     type Query: Serialize;
+    /// The serializable body type.
     type Body: Serialize;
+    /// The deserializable response type.
     type Response: DeserializeOwned;
 
-    // The endpoint relative path. Must start with a `/`
+    /// The endpoint relative path. Must start with a `/`
     fn relative_path(&self) -> Cow<str>;
 
-    // The request method.
+    /// The request method of this endpoint.
     fn method(&self) -> reqwest::Method;
 
+    /// The query to be used when calling this endpoint.
     fn query(&self) -> Option<&Self::Query> {
         None
     }
 
+    /// The body to be used when calling this endpoint.
     fn body(&self) -> Option<&Self::Body> {
         None
     }
 
+    /// The full path of this endpoint.
+    /// 
+    /// Automatically implemented.
     fn full_path(&self, is_sandbox: bool) -> String {
         if is_sandbox {
             format!("{}{}", SANDBOX_ENDPOINT, self.relative_path())
diff --git a/src/lib.rs b/src/lib.rs
index 22a2b9f..d7ee75e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -74,7 +74,7 @@
 //! - [ ] Webhooks Management API - 0.14.0
 //! - [ ] Payment Experience Web Profiles API - 1.0.0
 
-//#![deny(missing_docs)]
+#![deny(missing_docs)]
 
 pub mod api;
 pub mod countries;