There are some sentences that use "my" instead of "the" as in this example below, and I've never known when use it correctly.
Example: My neighbor's son is a doctor.
Could you guys write some common examples where use "my" instead of "the" as in this context that I used above?

Maybe I don't use it correctly because I always think ('s) as the meaning of "my" hahah, so I'm always writing "the" at the beginning of the sentence =D

See a translation

"My" is the first person singular possessive. So, when you use +'s it is typically in third person. (John's camera, Jessica's phone, Jane's car). "My" is how you determine possessive for yourself. I wouldn't say "foxwmulder's comment" if I was talking about something I wrote. It is MY comment.



Examples:

The neighbor's son is a doctor. - With no further context, I have no idea if the neighbor is related to to speaker at all. Are they the speaker's neighbor? Are they a fictional neighbor from a movie? Without being told more information or just knowing from situational context, there is no way to know from this sentence.

My neighbor's son is a doctor. - The "my" tells me that this neighbor is the speaker's neighbor. I immediately understand from this sentence who we are talking about.

If you were to write this in third person, it would look like "Lucas-BR's neighbor's son is a doctor." - You would not write this sentence. This is how I would tell someone else that your neighbor's son is a doctor.




The cat died. - Without more context, it is unclear which specific cat we are talking about. If you went over to your friend's house who has a cat and they said this, I would understand because there is previous context built into the conversation.

I will say that it does sound a little impersonal. Saying "the cat died" vs "my cat died" sounds colder? It either sounds like someone is having a hard time dealing with the fact that their cat died or they didn't really like the cat to begin with. This can happen with things you would assume someone wants to "own", so to speak.