What is the difference between primary and secondary sources? Examples needed.

I know this is like, day one stuff, but I keep mixing them up in my head. My professor keeps saying we need more primary sources, and I thought I was using them, but apparently not? Can someone just give me a super clear breakdown with examples?

My understanding is:

• Primary Sources: Are like, the original stuff, right? The thing you're actually studying.
• Secondary Sources: Are things about the original stuff. Someone else's interpretation.

But I need examples to make it stick. For a paper on the French Revolution:

• Is a letter written by a peasant during the revolution a primary or secondary source?
• What about a textbook chapter about the revolution?
• A documentary made in 2020 about the revolution?
• A painting created in 1793 of the revolution?

I think I know the answers, but I'm not 100% sure. If someone could break down each of those, it would seriously help me for my history paper. Thanks!

Paola, I literally had this exact confusion last semester!! Here's how my TA finally explained it that made it click:

Imagine you're studying a car crash.
Primary sources = The crashed cars, the police report filed that day, photos from the scene, witness statements given immediately.
Secondary sources = News articles about the crash, a documentary reenacting it, your professor's analysis of what caused it.

See the difference? Primary is the EVIDENCE itself. Secondary is people TALKING ABOUT the evidence.

For your French Revolution paper:

• Peasant letter = The witness statement (primary)
• 1793 painting = Photo from the scene (primary)
• Textbook = News article analysis (secondary)
• 2020 documentary = Documentary reenactment (secondary)

Your prof wants more primary because they want you working with evidence, not just summarizing what other historians said.