diff --git a/scrapy/link.py b/scrapy/link.py
index 704649731..0868ae5ef 100644
--- a/scrapy/link.py
+++ b/scrapy/link.py
@@ -4,6 +4,7 @@ This module defines the Link object used in Link extractors.
 For actual link extractors implementation see scrapy.linkextractors, or
 its documentation in: docs/topics/link-extractors.rst
 """
+from typing import Any
 
 
 class Link:
@@ -26,16 +27,20 @@ class Link:
 
     __slots__ = ["url", "text", "fragment", "nofollow"]
 
-    def __init__(self, url, text="", fragment="", nofollow=False):
+    def __init__(
+        self, url: str, text: str = "", fragment: str = "", nofollow: bool = False
+    ):
         if not isinstance(url, str):
             got = url.__class__.__name__
             raise TypeError(f"Link urls must be str objects, got {got}")
-        self.url = url
-        self.text = text
-        self.fragment = fragment
-        self.nofollow = nofollow
+        self.url: str = url
+        self.text: str = text
+        self.fragment: str = fragment
+        self.nofollow: bool = nofollow
 
-    def __eq__(self, other):
+    def __eq__(self, other: Any) -> bool:
+        if not isinstance(other, Link):
+            raise NotImplementedError
         return (
             self.url == other.url
             and self.text == other.text
@@ -43,12 +48,12 @@ class Link:
             and self.nofollow == other.nofollow
         )
 
-    def __hash__(self):
+    def __hash__(self) -> int:
         return (
             hash(self.url) ^ hash(self.text) ^ hash(self.fragment) ^ hash(self.nofollow)
         )
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return (
             f"Link(url={self.url!r}, text={self.text!r}, "
             f"fragment={self.fragment!r}, nofollow={self.nofollow!r})"