diff --git a/src/bin/my-tasks.rs b/src/bin/my-tasks.rs
deleted file mode 100644
index e7a11a9..0000000
--- a/src/bin/my-tasks.rs
+++ /dev/null
@@ -1,3 +0,0 @@
-fn main() {
-    println!("Hello, world!");
-}
diff --git a/src/cache.rs b/src/cache.rs
new file mode 100644
index 0000000..1b134e9
--- /dev/null
+++ b/src/cache.rs
@@ -0,0 +1 @@
+//! This module provides a local cache for CalDAV data
\ No newline at end of file
diff --git a/src/data/calendar.rs b/src/calendar.rs
similarity index 97%
rename from src/data/calendar.rs
rename to src/calendar.rs
index 8f8ee60..e74aada 100644
--- a/src/data/calendar.rs
+++ b/src/calendar.rs
@@ -3,8 +3,8 @@ use std::error::Error;
 
 use url::Url;
 
-use crate::data::Task;
-use crate::data::task::TaskId;
+use crate::task::Task;
+use crate::task::TaskId;
 
 use bitflags::bitflags;
 
diff --git a/src/data/client.rs b/src/client.rs
similarity index 96%
rename from src/data/client.rs
rename to src/client.rs
index 756b35c..36716ca 100644
--- a/src/data/client.rs
+++ b/src/client.rs
@@ -1,6 +1,4 @@
-//! Code to connect to a Caldav server
-//!
-//! Some of it comes from https://github.com/marshalshi/caldav-client-rust.git
+//! This module provides a client to connect to a CalDAV server
 
 use std::error::Error;
 use std::convert::TryFrom;
@@ -11,7 +9,7 @@ use minidom::Element;
 use url::Url;
 
 use crate::utils::{find_elem, find_elems};
-use crate::data::Calendar;
+use crate::calendar::Calendar;
 
 static DAVCLIENT_BODY: &str = r#"
     <d:propfind xmlns:d="DAV:">
@@ -200,7 +198,7 @@ impl Client {
             let mut this_calendar_url = self.url.clone();
             this_calendar_url.set_path(&calendar_href);
 
-            let supported_components = match crate::data::calendar::SupportedComponents::try_from(el_supported_comps.clone()) {
+            let supported_components = match crate::calendar::SupportedComponents::try_from(el_supported_comps.clone()) {
                 Err(err) => {
                     log::warn!("Calendar {} has invalid supported components ({})! Ignoring it.", display_name, err);
                     continue;
diff --git a/src/lib.rs b/src/lib.rs
index 4635634..0b0eb21 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,21 @@
-pub mod data;
+//! This crate provides a way to manage CalDAV data.
+//!
+//! It provides a CalDAV client in the [`client`] module, that can be used as a stand-alone module.
+//!
+//! Because the connection to the server may be slow, and a user-frendly app may want to quicky display cached data on startup, this crate also provides a local cache for CalDAV data in the [`cache`] module.
+//!
+//! These two "data sources" (actual client and local cache) can be used together in a [`Provider`](provider::Provider). \
+//! A `Provider` abstracts these two sources by merging them together into one virtual source. \
+//! It also handles synchronisation between the local cache and the server.
+
+mod calendar;
+pub use calendar::Calendar;
+mod task;
+pub use task::Task;
+
+pub mod client;
+pub mod provider;
+pub mod cache;
+
 pub mod settings;
 pub mod utils;
diff --git a/src/provider.rs b/src/provider.rs
new file mode 100644
index 0000000..926514d
--- /dev/null
+++ b/src/provider.rs
@@ -0,0 +1,3 @@
+//! This modules abstracts data sources and merges them in a single virtual one
+
+pub struct Provider {}
diff --git a/src/data/task.rs b/src/task.rs
similarity index 100%
rename from src/data/task.rs
rename to src/task.rs
diff --git a/src/data/mod.rs b/src/traits.rs
similarity index 69%
rename from src/data/mod.rs
rename to src/traits.rs
index 3c8e08a..6d530ef 100644
--- a/src/data/mod.rs
+++ b/src/traits.rs
@@ -1,17 +1,9 @@
-//! This module is the data source of the Caldav items
-//!
-//! This gives access to data from both the server and a local database for quick retrieval when the app starts
+//! This module provides CalDAV data sources and utilities
 
-use std::sync::Arc;
+/*
 use std::error::Error;
 
-pub mod calendar;
-mod task;
-pub mod client;
 
-pub use calendar::Calendar;
-pub use task::Task;
-use client::Client;
 
 /// A Caldav data source
 pub struct DataSource {
@@ -37,16 +29,21 @@ impl DataSource {
 
     /// Update the local database with info from the Client
     pub fn fetch_from_server(&mut self) {
-
+        // TODO: how to handle conflicts?
     }
 
     pub fn update_changes_to_server(&self) {
 
     }
 
+    // TODO: the API should force calling fetch_from_server before
     pub fn calendars(&self) -> Vec<&Calendar> {
+        // TODO: what happens when a user has a reference, which is modified/updated from the server? Conflict mut/not mut?
+        // TODO: how can the user modify Tasks from a non-mut reference?
         self.calendars
             .iter()
             .collect()
     }
 }
+
+*/
diff --git a/tests/caldav_client.rs b/tests/caldav_client.rs
index 2337666..25f04ec 100644
--- a/tests/caldav_client.rs
+++ b/tests/caldav_client.rs
@@ -9,7 +9,7 @@ use reqwest::header::CONTENT_TYPE;
 use minidom::Element;
 use url::Url;
 
-use my_tasks::data::client::Client;
+use my_tasks::client::Client;
 use my_tasks::settings::URL;
 use my_tasks::settings::USERNAME;
 use my_tasks::settings::PASSWORD;