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Understanding the difference betweenis andin in Python is really important — especially when you're trying to write clean and bug-free code. In this short guide, I’ve shared my learning and examples that helped me understand how these two operators work differently.

Theis operator checksidentity, not equality.

• It returnsTrue if two variables refer to thesame object in memory.
• It’s often used to check if something isNone.

a= [1,2,3]b=ac= [1,2,3]print(aisb)# True – same memory referenceprint(aisc)# False – different objects even if content is same

🔸 Useis when you care aboutobject identity, not just if values match.

A good use case:

x=NoneifxisNone:print("x has no value")

Thein operator checksmembership — it tells you if a value exists inside a list, string, tuple, dictionary, etc.

fruits= ["apple","banana","cherry"]print("banana"infruits)# Trueprint("grape"infruits)# False

It also works with strings:

text="hello world"print("world"intext)# Trueprint("python"intext)# False

• ❌ Usingis to compare values:

  a=1000b=1000print(aisb)# Might be False even though a == b

• ✅ Use== when comparing values, and useis for identity:

  print(a==b)# True

• ✅ Always useis None,not== None.

• Useis when comparing withNone or checking identity.
• Usein to check if a value exists inside something.
• Don't mix them up — Python won’t stop you, but your bugs will get harder to find!