diff --git a/lib/src/domain/command.rs b/lib/src/domain/command.rs
new file mode 100644
index 0000000..eeea41d
--- /dev/null
+++ b/lib/src/domain/command.rs
@@ -0,0 +1,21 @@
+/*
+  TIN - Time Tracking Application
+  Copyright (C) 2021  Julio Biason
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU Affero General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU Affero General Public License for more details.
+
+  You should have received a copy of the GNU Affero General Public License
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+pub trait Command {
+    fn execute(&self) -> Result<(), ()>;
+}
diff --git a/lib/src/domain/create_event.rs b/lib/src/domain/create_event.rs
new file mode 100644
index 0000000..de80ef1
--- /dev/null
+++ b/lib/src/domain/create_event.rs
@@ -0,0 +1,19 @@
+/*
+  TIN - Time Tracking Application
+  Copyright (C) 2020-2021  Julio Biason
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU Affero General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU Affero General Public License for more details.
+
+  You should have received a copy of the GNU Affero General Public License
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+struct CreateEvent {}
diff --git a/lib/src/domain/mod.rs b/lib/src/domain/mod.rs
new file mode 100644
index 0000000..a087a39
--- /dev/null
+++ b/lib/src/domain/mod.rs
@@ -0,0 +1,20 @@
+/*
+  TIN - Time Tracking Application
+  Copyright (C) 2021  Julio Biason
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU Affero General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU Affero General Public License for more details.
+
+  You should have received a copy of the GNU Affero General Public License
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+pub(crate) mod command;
+pub mod project;
diff --git a/lib/src/domain/project/create_project.rs b/lib/src/domain/project/create_project.rs
new file mode 100644
index 0000000..911a40b
--- /dev/null
+++ b/lib/src/domain/project/create_project.rs
@@ -0,0 +1,27 @@
+/*
+  TIN - Time tracking application
+  Copyright (C) 2021  Julio Biason
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU Affero General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU Affero General Public License for more details.
+
+  You should have received a copy of the GNU Affero General Public License
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+use crate::domain::command::Command;
+
+struct CreateProject(String);
+
+impl Command for CreateProject {
+    fn execute(&self) -> Result<(), ()> {
+        Ok(())
+    }
+}
diff --git a/lib/src/domain/project/mod.rs b/lib/src/domain/project/mod.rs
new file mode 100644
index 0000000..37ecbe0
--- /dev/null
+++ b/lib/src/domain/project/mod.rs
@@ -0,0 +1 @@
+pub mod create_project;