diff --git a/include_std/concepts b/include_std/concepts
new file mode 100644
index 0000000..fd44001
--- /dev/null
+++ b/include_std/concepts
@@ -0,0 +1,26 @@
+/*
+	This file is part of Fennix Kernel.
+
+	Fennix Kernel is free software: you can redistribute it and/or
+	modify it under the terms of the GNU General Public License as
+	published by the Free Software Foundation, either version 3 of
+	the License, or (at your option) any later version.
+
+	Fennix Kernel 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 General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with Fennix Kernel. If not, see <https://www.gnu.org/licenses/>.
+*/
+
+#pragma once
+
+#include <type_traits>
+
+namespace std
+{
+	template <class T>
+	concept integral = std::is_integral_v<T>;
+}
diff --git a/include_std/iterator b/include_std/iterator
index a10e5bf..22136cf 100644
--- a/include_std/iterator
+++ b/include_std/iterator
@@ -129,4 +129,10 @@ namespace std
 		std::advance(it, n);
 		return it;
 	}
+
+	struct default_sentinel_t
+	{
+	};
+
+	inline constexpr default_sentinel_t default_sentinel{};
 }
diff --git a/include_std/optional b/include_std/optional
new file mode 100644
index 0000000..c05bf17
--- /dev/null
+++ b/include_std/optional
@@ -0,0 +1,26 @@
+/*
+	This file is part of Fennix Kernel.
+
+	Fennix Kernel is free software: you can redistribute it and/or
+	modify it under the terms of the GNU General Public License as
+	published by the Free Software Foundation, either version 3 of
+	the License, or (at your option) any later version.
+
+	Fennix Kernel 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 General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with Fennix Kernel. If not, see <https://www.gnu.org/licenses/>.
+*/
+
+#pragma once
+
+#include <concepts>
+
+namespace std
+{
+	template <class T>
+	class optional;
+}
diff --git a/include_std/type_traits b/include_std/type_traits
index 7f833d5..5508a9f 100644
--- a/include_std/type_traits
+++ b/include_std/type_traits
@@ -284,6 +284,17 @@ namespace std
 	template <bool B>
 	using bool_constant = integral_constant<bool, B>;
 
+	template <class T>
+		struct is_integral : bool_constant < requires(T t, T *p, void (*f)(T))
+	{
+		reinterpret_cast<T>(t);
+		f(0);
+		p + t;
+	} > {};
+
+	template <class T>
+	constexpr bool is_integral_v = is_integral<T>::value;
+
 	typedef integral_constant<bool, true> true_type;
 	typedef integral_constant<bool, false> false_type;