diff --git a/flake.nix b/flake.nix
index e69de29..52ea7c0 100644
--- a/flake.nix
+++ b/flake.nix
@@ -0,0 +1,88 @@
+{
+  description = "NixOS configuration of Ryan Yin";
+
+  ##################################################################################################################
+  #
+  # Want to know Nix in details? Looking for a beginner-friendly tutorial?
+  # Check out https://github.com/ryan4yin/nixos-and-flakes-book !
+  #
+  ##################################################################################################################
+
+  # the nixConfig here only affects the flake itself, not the system configuration!
+  nixConfig = {
+    # substituers will be appended to the default substituters when fetching packages
+    # nix com    extra-substituters = [munity's cache server
+    extra-substituters = [
+      "https://nix-community.cachix.org"
+    ];
+    extra-trusted-public-keys = [
+      "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
+    ];
+  };
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-24.05";
+    home-manager.url = "github:nix-community/home-manager/release-24.05";
+    home-manager.inputs.nixpkgs.follows = "nixpkgs";
+
+    catppuccin-bat = {
+      url = "github:catppuccin/bat";
+      flake = false;
+    };
+  };
+
+  outputs = inputs @ {
+    self,
+    nixpkgs,
+    home-manager,
+    ...
+  }: {
+    nixosConfigurations = {
+      nixos-test = let
+        username = "phil";
+        specialArgs = {inherit username;};
+      in
+        nixpkgs.lib.nixosSystem {
+          inherit specialArgs;
+          system = "x86_64-linux";
+
+          modules = [
+            ./hosts/nixos-test
+            ./users/${username}/nixos.nix
+
+            home-manager.nixosModules.home-manager
+            {
+              home-manager.useGlobalPkgs = true;
+              home-manager.useUserPackages = true;
+
+              home-manager.extraSpecialArgs = inputs // specialArgs;
+              home-manager.users.${username} = import ./users/${username}/home.nix;
+            }
+          ];
+        };
+
+      msi-rtx4090 = let
+        username = "suzi"; # another username for this machine
+        specialArgs = {inherit username;};
+      in
+        nixpkgs.lib.nixosSystem {
+          inherit specialArgs;
+          system = "x86_64-linux";
+
+          modules = [
+            ./hosts/msi-rtx4090
+            ./users/${username}/nixos.nix
+
+            home-manager.nixosModules.home-manager
+            {
+              home-manager.useGlobalPkgs = true;
+              home-manager.useUserPackages = true;
+
+              home-manager.extraSpecialArgs = inputs // specialArgs;
+              home-manager.users.${username} = import ./users/${username}/home.nix;
+            }
+          ];
+        };
+    };
+  };
+}