In or on?

It is very interesting.
I also really want to know that...

Honestly, I don't know either but usually we can get a good idea by trying some examples.

I read it~: (read = present OR past)
in a newspaper
in a book
in a magazine
in a diary
in my notebook

I read it~: (read = present)
on the net
on the web
on the computer
on tv / on the tv
on the screen
on the wall

and it seems we use "read it OFF ~~" when we are talking about where we PREVIOUSLY (past) read something, or where we need to FOCUS (future) in order to get information,

I read it~ (read = past tense) / could you read it (read = present)~:
off the blackboard / ?
off the screen / ?
off the chart / ?
off the wall / ? (graffiti)
off John's notebook / ?
off Mario's computer / ?

***for this next part, you probably knew this already but I'll mention it anyway***:
"read it IN" can be used for locations where we read something:

I read~: (read = present OR past)
in the car (on the car = Reading while located on top of the car)
in my house (on my house = Reading while on the roof)

Anyways it seems we use 'read + 'in'' for hard copy things that we handle with our hands (like books). and we use 'read + 'on'' for everything else. (especially digital media)
So if you mistakenly said "I read it ON the newspaper" it would sound like you are not reading the newspaper's content but instead you are reading SOMETHING THAT IS ON TOP of the newspaper. (like a Post-it note or spilled Alphaghetti lol)
Anyways in casual speech nobody would even notice but if you are writing essays and stuff then yes, this would be important.
I'm no English teacher but I hope this helps!

To be honest, I don't think there are any subtle nuances and, even if there were, I don't think that knowing about them is going to help your English. We say these things because that's how everybody else talks.

One can open up a book or newspaper and see what's inside it. We normally don't see inside the internet or a TV. Only what is displayed on the screen.

I have to disagree somewhat with 王っさん。 There are subtle nuances in some cases. For example, if you said, "I read it on a book," implies you read it from the cover of the book, or there was something physically on the book you read. Normally, you would need a helping word, like "I read it on the cover of a book." I think Bodhisamaya's explanation is good.

I agree with Bodhisamaya also!
sooo basically...

think of 'in' as "inside"
think of 'on' as "on top"

although there are many exceptions.

I agree with Bodhisamaya-san and maikeru-san, and was planning to say something similar to what Bodhisamaya-san said before I read everyone else's responses. I think fiasko-san's examples point in this direction.

However, 王っさん makes a good point. In many cases, the preposition which sounds right to native speakers does not seem to follow any logic or any rule that can be simply stated, and there are differences between the prepositions used by US English speakers and UK English speakers. The following time expressions illustrate how arbitrary the "right" prepositions can be:

in the morning, in the evening, in the middle of the night
at night
at 8:00
at the end of the month
on/during the weekend
on Thursday(s)
yesterday, tomorrow (not preceded by a preposition)
last/next week/month/year (not preceded by a preposition)

One can probably find or invent rules to explain most of these, but they would have to be so complicated as to be nearly useless. To some extent, one has to learn what sounds natural to a native speaker simply by listening or reading a lot. I think this is 王っさん's point.

I think it's just the nuance that you open books, but you don't open the internet. Since the words are inside the books, you read things IN books.

I agree with 王っさん and tony. It might feel nice to "know" why we say "on the web", but the truth is that it won't really help you learn English. The best explanation anyone can give you is, "We say it that way because we say it that way." Don't think too much about it, because that will only make your head hurt.

Bodhisamaya is precisely correct. While some people here say that, "we just say things that way", I think that in this case, it is easy to apply Bodhisamaya's logic. When you have an item that you usually open up to read what is *inside*, you use "in". When you have an item that you don't usually open up, you use "on".

Therefore, since you must open up books, magazines, newspapers, and so on, you should use "in". To give another example to show why this is true, if you want to read a particular page in a book, you use "on". This is because, you do not open up the page to read what is inside it. You only do this with a book.

Therefore...

A: I read what was in the magazine.
B: I read what was on a page of the magazine.

Are both the correct forms. This is because, to read a page, you don't typically open it up. But to read the magazine, you must open it up to read what is inside.

Simply put, you use "in" when you are reading *inside* of something. You read what is inside of books, magazines, and newspapers. And what exactly is inside of books, magazines, and newspapers? Pages. You read what is *on* a particular page that is *in* a book, newspaper, or magazine.

I think we are all agreed that the "inside" criterion helps one to choose "in" over "on" in some cases. As I said, if other people had not pointed this out already, I would have suggested such a criterion myself. But as with most rules one tries to make about prepositions, it simply doesn't work all the time.

A: I read what was in the magazine.
OK, the logic is supposed to be that the writing is inside the magazine.
B: I read the part that was in fine print.
Here "in" has nothing to do with "inside"; it is an entirely different usage of "in"-- "written in fine print"
C: I read the writing in the sky written by the airplane.
Explaining that the writing is "inside the sky" is rather a stretch. In particular, the sky cannot be "opened up." "The writing on the sky" does not sound OK to me, however.
D: I read an essay on human rights.
On means "about, concerning" here; it has nothing to do with whether or not something can be opened up.

The "inside" criterion is helpful as far as it goes, but it is less helpful than some people are making it out to be. One can make up many such rules which work much of the time, just as one can make up rules about when to use は and when to use が which work much of the time for English speakers learning Japanese. The problem is that rules which are simple enough to remember and to apply easily almost always have a number of exceptions. I don't think that anyone is saying that such rules are useless; just that they cannot completely solve the problem of correct word choice.

Hi Tony,
I think that there are other uses of the word "in", as you point out. But I still think that Bodhisamaya's rule is quite helpful. When you have something that you can read "inside", you can use the word "in". All of the examples in the original post could be resolved with this rule, and none of the given counterexamples contradict this idea.

Exceptions do exist, but I believe that even the exceptions have some reason for their being in the history of their epistemology.

The "inside" criterion fits exactly with all of the "in" examples that the original poster gave, so I think that it is a very helpful rule.

Wow! Thank you for your wonderful comments a lot!!
I really apreciate you all natives give me live and usuful comments.

Love you!

Ciao.

To be continued...

kirbata-san, I don't disagree at all. If you look at the first comment I wrote, you will see that I said I agreed with Bodhisamaya-san and maikeru-san, and would have said something similar to what Bodhisamaya-san said if he had not already done so. It is a very helpful observation about these particular cases of usage.

I also think that 王っさん's point is helpful, if stated moderately-- that rules like this can only take one part of the way towards learning the usage of prepositions, and that eventually one has to rely on listening or reading experience. I was trying to reconcile these two contributions, and point out that both are helpful.

I don't know why this turned into a debate, with one "side" defending the "rule," and the other side defending the point of view that such rules are not enough in themselves. In my last comment I was trying to provide moderation again, but I probably should have let well enough alone.

Come on, everyone. Let's remember that we are writing these comments to try to be of assistance to the person who wrote the entry. Kyoko-san is likely to come to the conclusion that all English speakers are impossibly argumentative. ;-)