karasu ha kuroi.

Because は is being used as the topic particle, not as part of a regular word.

• As a normal hiragana character, は is read ha.
• But when it marks the topic of the sentence, it is pronounced wa.

So:

• カラスは黒い。
• read as Karasu wa kuroi.

This is one of the first spelling/pronunciation mismatches learners meet in Japanese.

は marks カラス as the topic of the sentence.

A natural way to think about it is:

• As for crows, they are black
• or Speaking of crows, they are black

In English, we often just say Crows are black or The crow is black, but Japanese often explicitly marks what the sentence is about.

So in:

• カラスは黒い。

the structure is roughly:

• カラス = crow / crows
• は = topic marker
• 黒い = is black / black

カラス is commonly written in katakana because animal names are often written that way, especially in simple or standard writing.

Possible writings include:

• カラス — very common
• からす — possible, but less common in many contexts
• 烏 or 鴉 — kanji exist, but they are less common and harder for many learners

Katakana is often used for:

• animal and plant names
• emphasis
• scientific or dictionary-style writing
• words that are easy to read in katakana form

So カラス is completely normal.

Because 黒い is an い-adjective.

In Japanese, many adjectives come in two major types:

• い-adjectives: like 黒い, 白い, 大きい
• な-adjectives: like 静か, 有名

The い at the end is part of the adjective itself, not a separate word.

So:

• 黒い = black

This kind of adjective can directly end a sentence:

• カラスは黒い。 = The crow is black. / Crows are black.

That is why you do not need です or だ for the sentence to be grammatical.

Because Japanese does not always need a separate verb like English is.

In this sentence, 黒い already functions as a complete predicate. That means it can serve as the main descriptive part of the sentence by itself.

So:

• カラスは黒い。 literally works as
• As for crows, black

but in natural English we translate it as:

• Crows are black
• The crow is black

Japanese often leaves out words that English requires.

Yes. カラスは黒いです。 is polite and very common.

Compare:

• カラスは黒い。 = plain style
• カラスは黒いです。 = polite style

Both are correct.

A small nuance:

• 黒い is the adjective
• です adds politeness
• です here is not exactly the same as English is

So learners should not think of 黒いです as black is. It is better to think of it as black in a polite sentence.

It can mean either, depending on context.

Japanese nouns usually do not change form for singular and plural the way English nouns do.

So カラス can mean:

• a crow
• the crow
• crows
• the crows

In this sentence, the most natural English translation is often:

• Crows are black

because it sounds like a general statement about the species.

But in another context, it could also mean:

• The crow is black

Japanese leaves number unspecified unless the context makes it clear.

Japanese does not have articles like a, an, and the.

So カラス by itself can mean:

• a crow
• the crow
• crows

You decide from context which English version fits best.

That is why one short Japanese sentence can match several English translations.

Because this sentence is making a statement about crows, not building a noun phrase like black crow.

Compare these ideas:

• カラスは黒い。 = Crows are black. / The crow is black.
• 黒いカラス = a black crow

So:

• 黒いカラス is a noun phrase: black crow
• カラスは黒い is a full sentence: the crow is black

This is a very important distinction in Japanese.

Yes, but the nuance changes.

• カラスは黒い。 = As for crows, they are black. / Crows are black.
• カラスが黒い。 = It is the crow that is black. / The crow is black.

Very roughly:

• は marks the topic
• が often marks the subject with more focus or contrast

So カラスは黒い sounds like a general statement or description of crows. カラスが黒い can sound more like you are identifying what is black.

For a beginner, は is the more natural choice for a simple general fact like this.

No, not in normal Japanese writing.

Japanese is usually written without spaces:

• カラスは黒い。

Spaces are often added in beginner materials to make the sentence easier to read and to show the different parts clearly.

So the spaced version is a teaching aid, while the standard written form is:

• カラスは黒い。

Its basic meaning is black, but like color words in English, it can also carry extended meanings depending on context.

For beginners, the main meaning is simply:

• 黒い = black

But in other contexts, it can suggest things like:

• dark
• suspicious
• morally shady

Still, in カラスは黒い。, it is just the ordinary color meaning.

A simple pronunciation guide is:

• カラスは黒い。
• karasu wa kuroi

Very rough English-style approximation:

• kah-rah-soo wah koo-roh-ee

A few helpful notes:

• ra in Japanese is not the same as English r; it is a light flap sound
• u in su is often light
• kuroi has two vowel parts at the end: ro-i, not one merged sound

If you are just starting, saying karasu wa kuroi clearly and evenly is a good goal.