Learn Hardcore Russian: Мой интернет быстрый.

The word мой is the masculine singular form of “my” in Russian and must agree with the grammatical gender and number of the noun интернет.

Nominative forms of “my”:

мой – masculine singular (e.g. мой интернет, мой дом)
моя – feminine singular (e.g. моя машина – my car)
моё – neuter singular (e.g. моё письмо – my letter)
мои – plural (e.g. мои друзья – my friends)

Since интернет is grammatically masculine, you must say мой интернет.

What gender is интернет and how can I tell?

Интернет is a masculine noun.

A common rule of thumb:

Nouns ending in a consonant → usually masculine
(e.g. стол, город, интернет)
Nouns ending in -а / -я → usually feminine
(e.g. машина, книга, неделя)
Nouns ending in -о / -е → usually neuter
(e.g. окно, море)

Because интернет ends in a consonant (-т), its default gender is masculine, so you use masculine forms with it: мой интернет, быстрый интернет, etc.

Why is it быстрый and not быстро?

Быстрый is an adjective (“fast”), and быстро is an adverb (“fast / quickly”).

In this sentence, we are describing a noun (интернет), so we need an adjective that agrees with that noun:

Мой интернет быстрый. – My internet (what kind of internet?) fast.

Use быстро when describing how an action is done (a verb):

Он говорит быстро. – He speaks fast.
Интернет работает быстро. – The internet works fast.

So:

Мой интернет быстрый. – correct (adjective with a noun)
Мой интернет быстро. – incorrect here (adverb with a noun)

Why is быстрый masculine? Shouldn’t it change somehow?

Yes, in Russian adjectives change form to agree with the noun in gender, number, and case.

The basic nominative singular forms of быстрый are:

быстрый – masculine (быстрый интернет)
быстрая – feminine (быстрая машина)
быстрое – neuter (быстрое соединение – fast connection)
быстрые – plural (быстрые компьютеры)

Since интернет is masculine singular nominative, the adjective must also be masculine singular nominative: быстрый.

What case are the words in Мой интернет быстрый?

Both интернет and быстрый (and the pronoun мой) are in the nominative case.

This is a simple “X is Y” sentence:

X (subject): мой интернет – nominative
Y (predicate adjective): быстрый – also nominative

In Russian, predicative adjectives like this appear in the nominative and agree with the subject:

Мой интернет быстрый.
Твоя связь медленная. – Your connection is slow.
Наши сервера надёжные. – Our servers are reliable.

Do I ever need to say есть here, like Мой интернет есть быстрый?

No, Мой интернет есть быстрый is not natural Russian.

For present-tense descriptions like this, you almost always omit есть:

Мой интернет быстрый. – correct and natural.

You do use есть:

To say that something exists or that you have something:
- У меня есть интернет. – I have internet.
Occasionally for strong emphasis or contrast:
- Интернет у меня есть быстрый, но дорогой.
  (very emphatic / stylistic: “Fast internet I do have, but it’s expensive.”)

In standard, neutral speech: Мой интернет быстрый.

Can I change the word order, like Интернет мой быстрый?

Russian word order is flexible, but it affects emphasis and naturalness.

Мой интернет быстрый. – neutral, the most natural version.
Интернет мой быстрый. – grammatical but sounds poetic or strongly emphatic, like:
“(As for) my internet, it is fast.”

More common alternatives with a shift of focus:

Интернет у меня быстрый. – “The internet that I have is fast,” emphasis on интернет.
Быстрый у меня интернет. – Emphasis on быстрый (“What I have is fast internet.”)

For normal everyday speech, stick with Мой интернет быстрый or У меня быстрый интернет.

What’s the difference between Мой интернет быстрый and У меня быстрый интернет?

Both can be translated as “My internet is fast,” but there’s a nuance:

Мой интернет быстрый.
Literally: My internet (is) fast.
– More like English, makes “my internet” the topic.
У меня быстрый интернет.
Literally: At me fast internet. → “I have fast internet.”
– Emphasizes possession (“what I have”) and is extremely common in Russian speech.

In practice:

Talking about your connection specifically: either is OK.
Talking more generally about what kind of internet you have:
У меня быстрый интернет sounds especially natural.

How do I pronounce Мой интернет быстрый?

Approximate pronunciation with stress marks:

Мой – [moy] (like “moy”) – one syllable.
интернет – [in-tɪr-NYET], stress on the last syllable: ин-тер-нет.
быстрый – [BYS-tryy], stress on the first syllable: бы-стрый.

A rough English-friendly rendering (stressed parts in CAPS):

MOY in-ter-NET BYS-tryy

Key points:

ой in мой sounds like “oy” in “boy”.
р is rolled or tapped, not like English “r”.
ы (in быстрый) is a special sound; think of a tense “i” in “bit,” but pronounced a bit farther back in the mouth.

Should интернет be capitalized: Интернет or интернет?

Today, the normal spelling is интернет with a lowercase и.

Historically, some sources wrote Интернет with a capital letter when referring to “the Internet” as a unique global network. Modern Russian style guides increasingly treat it as a common noun, like телефон or радио.

So in this sentence, you should write:

Мой интернет быстрый.

Can I say Мой интернет быстр instead of быстрый?

Yes, Мой интернет быстр is grammatically correct, but it sounds more formal, literary, or stylized.

быстрый – full form adjective, neutral and most common:
- Мой интернет быстрый. – normal, everyday Russian.
быстр – short form adjective, often used:
- in more formal or written style,
- for qualities presented as a state or result.

You can say:

Интернет у нас быстр и надёжен. – Our internet is fast and reliable.
(sounds like an advertisement or a formal statement)

In conversation, you’ll almost always hear быстрый, not быстр, in this context.