passed vs past

This pair confuses people because both can describe movement in the same sentence slot. The reliable difference is grammatical, not about meaning: passed is a verb form, and past is anything but a verb.

How to use passed

Passed is the past tense and past participle of pass. It always reports something happening.

• "He passed his driving test on the third attempt."
• "Three hours passed before anyone noticed."
• "She passed me the salt."
• "The bill has passed its second reading."

How to use past

Past works as four other parts of speech:

• Noun: "He never talks about his past."
• Adjective: "Sales have doubled over the past year."
• Preposition: "The bus goes past the hospital." "It's twenty past four."
• Adverb: "She waved as she ran past."

The test

Put the sentence into the present tense. If the word becomes pass or passes, you needed passed. "He passed the shop" becomes "He passes the shop" — a working sentence, so passed is right. "He walked past the shop" becomes "He walks past the shop" — past stays put, because it is not the verb. The verb there is walk.

That test explains the tricky pair below.

The edge case: passed vs walked past

Both of these are correct, and they mean nearly the same thing:

• "I passed the bakery on the way home." (pass is the verb)
• "I walked past the bakery on the way home." (walk is the verb; past is a preposition)

What you cannot write is "I walked passed the bakery" — that gives the sentence two verbs and no preposition. Whenever another verb is already present (walked, drove, ran, flew, went, sailed), the following word is past.

One more nuance: with time, "the past few weeks" uses past as an adjective, while "a few weeks passed" uses the verb. And "passed away" is always the verb spelling.