Learn Hardcore Russian: Пожалуйста, не трогай мою книгу.

It can mean “please” when asking for something or making a request:
- Пожалуйста, не трогай мою книгу. – Please, don’t touch my book.
It can also mean “you’re welcome” as a response to спасибо (thank you):
- — Спасибо. — Пожалуйста. – — Thank you. — You’re welcome.
It can sometimes be used like “here you are” / “there you go” when handing something:
- Вот ваша книга, пожалуйста. – Here is your book, here you are.

So the core idea is politeness and willingness to comply or ask kindly; the exact English equivalent depends on context.

Is пожалуйста necessary in this sentence, and where can it go?

It is not grammatically necessary; it just makes the request more polite. All of these are correct, with slightly different tone:

Не трогай мою книгу. – Don’t touch my book. (direct, can sound a bit sharp)
Пожалуйста, не трогай мою книгу. – Please don’t touch my book. (polite, standard)
Не трогай мою книгу, пожалуйста. – Don’t touch my book, please. (same meaning; prosody may feel more insistent)
Не трогай, пожалуйста, мою книгу. – Also possible; пожалуйста is framed as a polite softener.

Russian word order is relatively flexible, and пожалуйста can appear at the beginning, in the middle, or at the end to soften the command.

Why is it не трогай and not something like не трогаешь for “don’t touch”?

Не трогай is an imperative form – a direct command or request.

трогаешь is 2nd person singular present indicative:
- Ты трогаешь мою книгу. – You are touching my book. (a statement of fact)
трогай is 2nd person singular imperative:
- Трогай мою книгу. – Touch my book. / Go ahead and touch my book.
With не, the imperative becomes a negative command:
- Не трогай мою книгу. – Don’t touch my book.

So English uses do + not + verb for commands (don’t touch), but Russian uses не + imperative form of the verb.

How is the imperative form трогай formed from трогать?

The verb is трогать (to touch). To get the ты (informal singular) imperative:

Take the 3rd person plural present:
- они трóгают – they touch
Remove -ют: трога-
Add -й: трогай

So:

трогать → трóгают → трогай

Pronunciation and stress:

трóгать – ТРÓ-гать
трóгай – ТРÓ-гай

The stress stays on the first syllable.

What is the difference between не трогай and не трогайте?

Both are negative imperatives, but they differ in person / politeness:

Не трогай мою книгу.
- ты-form (singular, informal)
- Used with one person you address as ты: a friend, child, sibling, someone close or younger.
Не трогайте мою книгу.
- вы-form (plural or formal)
- Used when speaking to:
  - More than one person, or
  - One person politely / formally (stranger, colleague, older person, etc.).

English has only you, but Russian distinguishes informal ты and formal/plural вы, and the imperative must agree with that.

Why is it мою книгу and not моя книга?

Because мою книгу is in the accusative case, used for the direct object of the verb.

книга is the subject (nominative):
- Моя книга на столе. – My book is on the table.
книгу is the direct object (accusative):
- Я читаю мою книгу. – I am reading my book.
- Не трогай мою книгу. – Don’t touch my book.

The possessive pronoun мой also changes to match the case, gender, and number of the noun:

Nominative feminine: моя книга – my book (as subject)
Accusative feminine inanimate: мою книгу – my book (as object)

So моя книга would sound like “my book (is) don’t touch” – wrong grammar.

What gender and case are мою and книгу, and how can I tell?

книга is feminine, singular, nominative as a dictionary form.
- Ending -а is a common marker of feminine nouns.
In this sentence we have книгу:
- feminine, singular, accusative (direct object).
- Nominative -а → accusative -у: книга → книгу.

The possessive pronoun мой declines to agree with the noun:

Feminine nominative: моя книга
Feminine accusative: мою книгу

So both мою and книгу are feminine singular accusative, and they agree with each other in gender, number, and case.

Could I just say Пожалуйста, не трогай книгу without мою?

Yes, that is completely correct:

Пожалуйста, не трогай книгу. – Please don’t touch the book.

The difference is:

мою книгу – clearly your book, emphasizes ownership.
книгу – the book in context (e.g., a particular book both speakers know about, or any book nearby that’s understood from context).

If it is important that it is specifically your book, keep мою. If the context already makes it obvious whose book it is, you can omit мою.

Why is the imperfective verb трогать used here and not the perfective тронуть?

Russian has aspect: imperfective vs perfective.

трогать – imperfective: the general action of touching, process, or repeated actions.
тронуть – perfective: a single, completed act of touching (to touch once / to give a small touch).

In negative commands, the imperfective is usually used to mean “don’t do this action at all / in general”:

Не трогай мою книгу. – Don’t touch my book (at all, don’t engage in touching it).

You can hear:

Не тронь мою книгу. – Don’t you dare touch my book (even once).

This sounds more abrupt, sharper, or more emotionally charged, often with a nuance of “not even once”. The sentence you gave is more neutral and standard.

Is не трогай мою книгу very rude, or is it acceptable as a normal request?

Tone depends heavily on context, intonation, and relationship:

With neutral or friendly intonation to a child, sibling, or close friend,
- Не трогай мою книгу. is normal, not necessarily rude.
Adding пожалуйста makes it clearly more polite:
- Пожалуйста, не трогай мою книгу.

To be especially polite, especially with strangers or in formal contexts, use вы:

Пожалуйста, не трогайте мою книгу.

To sound softer and less direct, Russians might use phrasing like:

Лучше не трогай мою книгу. – You’d better not touch my book.
Я бы попросил(а) вас не трогать мою книгу. – I’d like to ask you not to touch my book. (formal, quite polite)

So the basic sentence is not inherently rude, but without пожалуйста and with sharp intonation it can sound like a firm order.

Can the word order change, or must it stay Пожалуйста, не трогай мою книгу?

Russian allows several natural word orders here. All of these are grammatical:

Пожалуйста, не трогай мою книгу. – very common, standard.
Не трогай мою книгу, пожалуйста. – also very common.
Не трогай, пожалуйста, мою книгу. – a bit more emphatic around пожалуйста.
Мою книгу не трогай, пожалуйста. – brings focus to мою книгу (“my book, in particular, don’t touch”).

The core verb phrase не трогай мою книгу stays together; moving пожалуйста or мою книгу mainly affects emphasis and rhythm, not basic meaning.

Are there other verbs I could use instead of трогать, and how would the meaning change?

Yes, different verbs give slightly different nuances:

Не трогай мою книгу. – Don’t touch my book (don’t put your hands on it / disturb it).
Не прикасайся к моей книге. – Don’t touch my book (more formal/literary; uses preposition к
- dative к моей книге).
Не бери мою книгу. – Don’t take / pick up my book.
Не открывай мою книгу. – Don’t open my book.
Не листай мою книгу. – Don’t flip through my book.

Трогать is the most general “touch” verb; it focuses on physical contact, whether brief or longer. Other verbs add more specific actions.

How do you pronounce this whole sentence, and where are the stresses?

Word by word with stress marked:

Пожа́луйста – po-ЖА́-luy-sta
не – ne (unstressed)
трóгай – ТРÓ-gai
мою́ – ma-Ю́
кни́гу – КНИ́-gu

Together (approximate English-friendly transcription):

Пожа́луйста, не трóгай мою́ кни́гу.
[pa-ZHA-looy-sta, nyeh TRO-gai ma-YU KNEE-goo]

Key points:

Пожа́луйста has stress on жа.
трóгай has stress on тро.
мою́ is stressed on ю, so the мо- is very weak.
кни́гу keeps the stress on the first syllable, same as кни́га.