diff --git a/include/Activation/Activation.hpp b/include/Activation/Activation.hpp
new file mode 100644
index 0000000..e51f6f7
--- /dev/null
+++ b/include/Activation/Activation.hpp
@@ -0,0 +1,16 @@
+#include <functional>
+#include <Eigen/Dense>
+#include <Layers/Layers.hpp>
+
+class Activation : public Layer {
+public:
+    Activation(std::function<Eigen::VectorXd(const Eigen::VectorXd&)> activation,
+               std::function<Eigen::VectorXd(const Eigen::VectorXd&)> activation_prime);
+
+    void forward(const Eigen::VectorXd& input) override;
+    void backward(const Eigen::VectorXd& output_gradient, double learning_rate) override;
+
+private:
+    std::function<Eigen::VectorXd(const Eigen::VectorXd&)> activation;
+    std::function<Eigen::VectorXd(const Eigen::VectorXd&)> activation_prime;
+};
diff --git a/include/Layers/Layers.hpp b/include/Layers/Layers.hpp
new file mode 100644
index 0000000..a5f1239
--- /dev/null
+++ b/include/Layers/Layers.hpp
@@ -0,0 +1,22 @@
+#ifndef LAYERS_HPP
+#define LAYERS_HPP
+
+#include <Eigen/Dense>
+
+class Layer {
+public:
+    Layer();
+
+    virtual void forward(const Eigen::VectorXd& input_data);
+    virtual void backward(const Eigen::VectorXd& output_gradient, double learning_rate);
+
+    const Eigen::VectorXd& getOutput() const;
+    const Eigen::VectorXd& getInputGradient() const;
+
+protected:
+    Eigen::VectorXd input;
+    Eigen::VectorXd output;
+    Eigen::VectorXd input_gradient;
+};
+
+#endif // LAYERS_HPP
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 1c1e37d..4cc2614 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -9,6 +9,8 @@ set(CMAKE_CXX_STANDARD 11)
 include_directories(include)
 include_directories(${CMAKE_SOURCE_DIR}/include)
 include_directories(${CMAKE_SOURCE_DIR}/Eigen)
+include_directories(${CMAKE_SOURCE_DIR}/include/Activation)
+include_directories(${CMAKE_SOURCE_DIR}/include/Layers)
 
 # Add source files to the project
 file(GLOB_RECURSE SOURCES "src/*.cpp")