diff --git a/src/phase/lexer/tokenizer/keyword.ts b/src/phase/lexer/tokenizer/keyword.ts
index 2c927f53..e9402447 100644
--- a/src/phase/lexer/tokenizer/keyword.ts
+++ b/src/phase/lexer/tokenizer/keyword.ts
@@ -45,6 +45,13 @@ export const keywordMaps: KeywordMap[] = [
             [LanguageID.LanguagePersian]: ["تابع"],
         },
     },
+    {
+        id: TokenKeywordType.TOKEN_EXTERN,
+        data: {
+            [LanguageID.LanguageEnglish]: ["extern"],
+            [LanguageID.LanguagePersian]: ["ارث"],
+        },
+    },
     {
         id: TokenKeywordType.TOKEN_FOR,
         data: {
diff --git a/src/phase/lexer/tokenizer/type.ts b/src/phase/lexer/tokenizer/type.ts
index d97f03cc..62a6ac8e 100644
--- a/src/phase/lexer/tokenizer/type.ts
+++ b/src/phase/lexer/tokenizer/type.ts
@@ -21,6 +21,7 @@ export enum TokenKeywordType {
     TOKEN_ELSE = "ELSE",
     TOKEN_PRINT = "PRINT",
     TOKEN_FN = "FN",
+    TOKEN_EXTERN = "EXTERN",
     TOKEN_FOR = "FOR",
     TOKEN_WHILE = "WHILE",
     TOKEN_REPEAT = "REPEAT",
diff --git a/src/phase/parser/parse/ast/extern.ts b/src/phase/parser/parse/ast/extern.ts
new file mode 100644
index 00000000..51c9e6ca
--- /dev/null
+++ b/src/phase/parser/parse/ast/extern.ts
@@ -0,0 +1,29 @@
+import { AstNode } from './node';
+import { AstType } from './expression/type';
+import { stringify } from './../../../../serializer';
+import { AstFunctionArgument } from './function/function_argument';
+
+export class AstExtern extends AstNode {
+    name: string;
+    args: AstFunctionArgument[];
+    return_type: AstType;
+    generate_name: string;
+
+    constructor(name: string, args: AstFunctionArgument[], return_type: AstType, generate_name: string) {
+        super("Extern");
+        this.name = name;
+        this.args = args;
+        this.generate_name = generate_name;
+        this.return_type = return_type;
+    }
+
+    stringify(wantsJson: boolean = true): string | object {
+        const obj: object = {
+            name: this.name,
+            args: this.args,
+            return_type: this.return_type.stringify(false),
+            generate_name: this.generate_name,
+        };
+        return stringify(obj, wantsJson);
+    }
+};
diff --git a/src/phase/parser/parse/ast/program.ts b/src/phase/parser/parse/ast/program.ts
index 878629fe..2918b483 100644
--- a/src/phase/parser/parse/ast/program.ts
+++ b/src/phase/parser/parse/ast/program.ts
@@ -1,5 +1,6 @@
 import { AstNode } from './node';
 import { AstBlock } from './block';
+import { AstExtern } from './extern';
 import { AstLayout } from './layout/layout';
 import { stringify } from './../../../../serializer';
 import { LanguageMap } from './../../../../common/language/language';
@@ -8,6 +9,7 @@ import { AstFunctionDeclaration } from './function/function_declaration';
 export class AstProgram extends AstNode {
     errors: string[] = [];
     layout: AstLayout | undefined;
+    externs: AstExtern[];
     functions: AstFunctionDeclaration[];
     language: LanguageMap;
     block: AstBlock;
@@ -15,6 +17,7 @@ export class AstProgram extends AstNode {
     constructor(language: LanguageMap, block: AstBlock | undefined = undefined) {
         super("Program");
         this.functions = [];
+        this.externs = [];
         this.language = language;
         if (block === undefined) {
             this.block = RuntimeBlock.generate();
@@ -42,6 +45,11 @@ export class AstProgram extends AstNode {
         return false;
     }
 
+    pushExtern(extern: AstExtern): boolean {
+        this.externs.push(extern);
+        return true;
+    }
+
     pushFunctionDeclaration(function_declaration: AstFunctionDeclaration): boolean {
         if (this.hasFunctionDeclaration(function_declaration)) {
             return false;
diff --git a/src/phase/parser/parse/extern.ts b/src/phase/parser/parse/extern.ts
new file mode 100644
index 00000000..7e9c08a1
--- /dev/null
+++ b/src/phase/parser/parse/extern.ts
@@ -0,0 +1,64 @@
+import { Parser } from './parser';
+import { AstBlock } from './ast/block';
+import { AstExtern } from './ast/extern';
+import { parseType } from './expression/type';
+import { AstType } from './ast/expression/type';
+import { AstFunctionArgument } from './ast/function/function_argument';
+import { parserMessageRenderer } from '../../../common/message/message';
+import { ParserMessageKeys } from '../../../common/message/parser/parser';
+import { parserParseFunctionArguments } from './function/function_attributes';
+import { TokenKeywordType, TokenOperatorType } from '../../lexer/tokenizer/type';
+
+export function parserParseExtern(parser: Parser, parent_block: AstBlock): AstExtern | undefined {
+    parser.expect(TokenKeywordType.TOKEN_EXTERN);
+
+    if (parser.skip(TokenKeywordType.TOKEN_FN)) {
+
+    }
+    if (! parser.currentToken.isKeyword) {
+        parser.pushError(parserMessageRenderer(parser.getLanguageId(), ParserMessageKeys.PARSER_FUNCTION_NAME_IS_NOT_VALID_IDENTIFIER));
+        return undefined;
+    } else if (parser.currentToken.isDefinedIdentifier) {
+        parser.pushError(parserMessageRenderer(parser.getLanguageId(), ParserMessageKeys.PARSER_FUNCTION_NAME_IS_RESERVED_IN_SALAM));
+        return undefined;
+    }
+
+    const name: string | undefined = parser.currentToken.data?.getValueString();
+    if (name === undefined) {
+        parser.pushError(parserMessageRenderer(parser.getLanguageId(), ParserMessageKeys.PARSER_FUNCTION_NAME_IS_NOT_VALID));
+        return undefined;
+    }
+
+    // Eating function name
+    parser.next();
+
+    const params: AstFunctionArgument[] | undefined = parserParseFunctionArguments(parser);
+    if (! params) {
+        parser.pushError(parserMessageRenderer(parser.getLanguageId(), ParserMessageKeys.PARSER_FUNCTION_PARAMETERS_ARE_NOT_VALID));
+        return undefined;
+    }
+
+    let return_type: AstType | undefined = undefined;
+    if (parser.skip(TokenOperatorType.TOKEN_MEMBER_POINTER)) {
+        return_type = parseType(parser);
+        if (return_type === undefined) {
+            parser.pushError("Invalid data type as return type of function " + name);
+            return undefined;
+        }
+    }
+    
+    if (return_type === undefined) {
+        return_type = AstType.createVoid();
+    }
+
+    parser.expect(TokenOperatorType.TOKEN_COLON);
+    const generate_name: string | undefined = parser.currentToken.data?.getValueString();
+    if (generate_name === undefined) {
+        parser.pushError("Invalid data as generate name of an externed function.");
+        return undefined;
+    }
+    parser.expect(TokenKeywordType.TOKEN_IDENTIFIER);
+
+    const ast: AstExtern = new AstExtern(name, params, return_type, generate_name);
+    return ast;
+};
diff --git a/src/phase/parser/parse/parse.ts b/src/phase/parser/parse/parse.ts
index 5a228f22..e90349d0 100644
--- a/src/phase/parser/parse/parse.ts
+++ b/src/phase/parser/parse/parse.ts
@@ -7,6 +7,8 @@ import { ParserMessageKeys } from './../../../common/message/parser/parser';
 import { AstFunctionDeclaration } from './ast/function/function_declaration';
 import { TokenKeywordType, TokenOtherType } from './../../lexer/tokenizer/type';
 import { parserParseFunctionDeclaration } from './function/function_declaration';
+import { AstExtern } from './ast/extern';
+import { parserParseExtern } from './extern';
 
 export function parse(parser: Parser): void {
     while (parser.index < parser.lexer.tokens.length) {
@@ -14,6 +16,16 @@ export function parse(parser: Parser): void {
 
         if (token.type === TokenOtherType.TOKEN_EOF) {
             break;
+        } else if (token.type === TokenKeywordType.TOKEN_EXTERN) {
+            const extern: AstExtern | undefined = parserParseExtern(parser, parser.ast.block);
+            if (! extern) {
+                parser.pushError(parserMessageRenderer(parser.getLanguageId(), ParserMessageKeys.PARSER_FAILED_TO_PARSE_FUNCTION_STATEMENT));
+                break;
+            }
+            if (! parser.ast.pushExtern(extern)) {
+                parser.pushError(parserMessageRenderer(parser.getLanguageId(), ParserMessageKeys.PARSER_FAILED_TO_PARSE_FUNCTION));
+                break;
+            }
         } else if (token.type === TokenKeywordType.TOKEN_FN) {
             const function_declaration: AstFunctionDeclaration | undefined = parserParseFunctionDeclaration(parser, parser.ast.block);
             if (! function_declaration) {
diff --git a/src/runtime/block/runtime_bock.ts b/src/runtime/block/runtime_bock.ts
index 2f22a399..411dd2bd 100644
--- a/src/runtime/block/runtime_bock.ts
+++ b/src/runtime/block/runtime_bock.ts
@@ -30,9 +30,9 @@ export class RuntimeBlock {
         version_type.setSyetem();
         block.symbol_table.addSystemSymbol("version", version_type);
 
-        const int2str_type: AstType = AstType.createFunction("int2str", "int2str", [new AstFunctionArgument("value", AstType.createInt())], AstType.createString());
-        int2str_type.setSyetem();
-        block.symbol_table.addSystemSymbol("int2str", int2str_type);
+        // const int2str_type: AstType = AstType.createFunction("int2str", "int2str", [new AstFunctionArgument("value", AstType.createInt())], AstType.createString());
+        // int2str_type.setSyetem();
+        // block.symbol_table.addSystemSymbol("int2str", int2str_type);
         const float2str_type: AstType = AstType.createFunction("float2str", "float2str", [new AstFunctionArgument("value", AstType.createFloat())], AstType.createString());
         float2str_type.setSyetem();
         block.symbol_table.addSystemSymbol("float2str", float2str_type);
diff --git a/src/test.c b/src/test.c
index 7a97cc18..cce6b5c9 100644
--- a/src/test.c
+++ b/src/test.c
@@ -8,15 +8,10 @@
 #include <ctype.h>
 
 // Sign functions
-char* _int2str(int a);
 char* test();
 char* main();
 
 // Functions
-char* _int2str(int a) {
-return ("110");
-}
-
 char* test() {
 char* a = (char*) malloc(strlen("Hey ") + 1);
 if (a == NULL) {
diff --git a/src/test.json b/src/test.json
index 65106af4..9e6be1a2 100644
--- a/src/test.json
+++ b/src/test.json
@@ -1,53 +1,6 @@
 {
   "type": "Program",
   "functions": [
-    {
-      "name": "_int2str",
-      "args": [
-        {
-          "type": "FunctionArgument",
-          "name": "a",
-          "value_type": {
-            "type": "Type",
-            "is_system": false,
-            "is_primitive": false,
-            "type_kind": "int",
-            "is_pointer": false,
-            "is_reference": false,
-            "is_array": false,
-            "members": [],
-            "func_args": []
-          },
-          "is_optional": false
-        }
-      ],
-      "body": {
-        "children": [
-          {
-            "type": "Return",
-            "value": {
-              "type": "ExpressionLiteral",
-              "value_type": {
-                "type": "Type",
-                "is_system": false,
-                "is_primitive": true,
-                "type_kind": "string",
-                "is_pointer": false,
-                "is_reference": false,
-                "is_array": false,
-                "members": [],
-                "func_args": []
-              },
-              "value": "110"
-            }
-          }
-        ]
-      },
-      "return_type": {
-        "type": "Type",
-        "type_kind": "string"
-      }
-    },
     {
       "name": "test",
       "args": [],
diff --git a/src/test.salam b/src/test.salam
index a01996ee..ed48a86e 100644
--- a/src/test.salam
+++ b/src/test.salam
@@ -1,8 +1,8 @@
-// extern 
+extern fn int2str() -> string: int2str
 
-fn _int2str(int a) -> string:
-    ret "110"
-end
+// fn _int2str(int a) -> string:
+//     ret "110"
+// end
 
 fn test -> string:
     string a = "Hey "