Я иду домой один.

Идти is the dictionary form, meaning to go / to be going on foot.

In the sentence, you need a conjugated verb, because the speaker is saying I am going.
So идти changes to иду, which is the 1st person singular form:

• я иду — I am going
• ты идёшь — you are going
• он / она идёт — he / she is going

So Я иду домой один literally starts with I am going...

This is a very common question because Russian has two common verbs for go on foot:

• идти / иду — going in one direction, right now, or on one specific trip
• ходить / хожу — going habitually, repeatedly, or in various directions

So:

• Я иду домой = I’m going home / I’m on my way home
• Я хожу домой пешком = I go home on foot / I walk home (in general, habitually)

In your sentence, the speaker is talking about a specific trip home, so иду is the natural choice.

Домой is a special word meaning homeward / to home / home when talking about movement toward home.

So:

• Я иду домой — I’m going home

This is different from:

• в дом — into the house
• к дому — toward the house / up to the house

Домой is used when home is meant in the everyday personal sense, not just any physical building.

Compare:

• Я дома — I am at home
• Я иду домой — I am going home

That pair is worth memorizing.

In modern Russian, домой is usually treated as an adverb.

Even though historically it comes from an older case form of дом, learners should usually think of it as a fixed word meaning homeward or home after verbs of motion.

That is why you simply memorize expressions like:

• идти домой
• ехать домой
• вернуться домой

You do not usually analyze it as an ordinary noun form the way you would with regular case endings.

Yes, один can mean one, but it also often means alone / by oneself, depending on context.

In this sentence:

• Я иду домой один

один means alone, not the number one.

So the idea is:

• I’m going home alone
• I’m going home by myself

Russian uses один / одна / одно / одни this way quite naturally.

Because один agrees with the speaker.

In this sentence, я does not show gender by itself, but один does. So:

• Я иду домой один — said by a man
• Я иду домой одна — said by a woman

This is a very important feature of Russian: words like this often show information that English does not.

Yes, you can think of it that way. It behaves like a word that agrees with the subject in gender and number, and here it acts like a predicative adjective-like word meaning alone.

That is why it changes:

• Я один — I am alone (male speaker)
• Я одна — I am alone (female speaker)
• Мы одни — We are alone

In your sentence, it describes the state of the subject while going home.

Yes, very often.

Russian often drops subject pronouns when the verb already makes the subject clear:

• Иду домой один — I’m going home alone

Because иду already means I am going, я is not always necessary.

Including я can add clarity, contrast, or emphasis:

• Я иду домой один, а не с друзьями — I’m going home alone, not with friends.

So both are correct, but with slightly different emphasis.

No, Russian word order is fairly flexible. The basic version is natural and neutral:

• Я иду домой один

But you may also hear:

• Домой я иду один
• Я один иду домой
• Один я иду домой

These versions shift emphasis or sound more stylistic.

For a learner, the safest neutral order is the original one:

• Я иду домой один

Grammatically, it is present tense. But in English, the best translation often depends on context.

• Я иду домой can mean I’m going home
• Sometimes, depending on context, it can also be translated I’m on my way home

Because идти describes motion happening now or on a specific trip, English usually prefers the progressive form am going rather than the simple present go.

Because the main verb is already иду = am going / go.

English uses I am going, where am is an auxiliary helping form the progressive. Russian does not build this idea the same way. The single verb иду already carries the meaning.

So:

• Я иду = I am going

There is no separate word for am needed here.

The standard stress is:

• Я идУ домОй одИн

So the stressed syllables are:

• иду́
• домо́й
• оди́н

Stress matters in Russian, so it is good to learn words together with their stress.

Normally, no. Домой strongly suggests home in the personal sense, not just to the house as a building.

If you specifically meant to the house, Russian would more likely use something like:

• Я иду к дому — I’m going toward the house
• Я иду в дом — I’m going into the house

So домой is best understood as home.

Yes, it can, but the emphasis changes a little.

For example:

• Я иду домой один — neutral: I’m going home alone
• Я иду один домой — also possible, with a slightly different rhythm or emphasis

Russian allows this kind of movement more than English does. Still, for a learner, Я иду домой один is the clearest and most standard version to use first.