Везде было тихо.

Because this is an impersonal sentence.

In English, we often say it was quiet, even though it does not refer to anything specific. Russian often does something similar, but without an explicit subject. In the past tense, these impersonal sentences commonly use the neuter singular form of the verb:

• было = past tense, neuter singular of быть

So Везде было тихо literally works like Everywhere, it was quiet, with the it left unspoken.

Because тихо here is not describing a noun directly.

Forms like:

• тихий
• тихая
• тихое
• тихие

are adjective forms, and they must agree with a noun:

• тихий город = a quiet city
• тихая комната = a quiet room

But in Везде было тихо, there is no noun being described. Instead, тихо means quiet as a general state or condition: it was quiet.

So тихо functions as a predicative word / adverb-like form, not as a regular adjective agreeing with a noun.

Везде is an adverb meaning everywhere.

Since it is an adverb:

• it does not change for case
• it does not change for gender
• it does not change for number

It simply tells you where the state applies.

None. Везде is an adverb, so it is not in a case.

This is a very common question for English speakers, because many Russian location expressions involve prepositions plus noun cases, such as:

• в доме = in the house
• на улице = on the street

But везде is a standalone adverb, so there is no case ending to analyze.

Not exactly a missing subject in the usual sense. Russian simply allows this kind of subjectless impersonal construction.

English usually needs something:

• It was quiet everywhere

Russian does not need a dummy subject like it, so it just says:

• Везде было тихо

So the sentence is complete as it stands.

Yes. Russian word order is flexible, but changing it changes the focus or emphasis.

The most neutral version is:

• Везде было тихо.

Other possible orders include:

• Было тихо везде.
• Тихо было везде.

These are still understandable, but they may sound more marked, more literary, or more focused on a particular part of the sentence.

For a learner, Везде было тихо is the safest and most natural default.

The stress is:

• вездЕ
• бЫло
• тИхо

A simple pronunciation guide:

• везде ≈ vyez-DYE
• было ≈ BYE-luh
• тихо ≈ TEE-khuh

A more connected pronunciation of the whole sentence:

• вездЕ было тИхо

The х sound in тихо is like the ch in Scottish loch or German Bach, not like English h.

Yes. Всюду is a close synonym of везде and also means everywhere.

So both are natural:

• Везде было тихо.
• Всюду было тихо.

In many contexts they are interchangeable. Learners will often meet везде first, and it is very common in everyday speech.

Because in Russian, the verb быть is normally omitted only in the present tense, not in the past.

Compare:

• Везде тихо. = It is quiet everywhere.
• Везде было тихо. = It was quiet everywhere.

So in the present, Russian often has no visible is. But in the past, you need the past-tense form:

• было

Yes. Тихо can be used in different ways.

As an adverb:

• Он говорил тихо. = He spoke quietly.

As a predicative state, like in your sentence:

• В комнате было тихо. = The room was quiet. / It was quiet in the room.
• Везде было тихо. = It was quiet everywhere.

So the same form тихо can mean either:

• quietly when modifying a verb
• quiet when describing a situation or environment

You understand which one it is from the sentence structure.