Does Russian have the concept of "sentence fragments" (as English does)?

Question

Question: Does Russian have the concept of "sentence fragments" (as English does), and is it also clearly considered a grammatical mistake?

For an optional bonus part of this question, not required though, could you provide a link to a webpage discussing sentence fragments in Russian?

Further explanation:

In English grammar, you may have heard about a "sentence fragment".

"Sentence fragments are groups of words that look like sentences, but aren't. To be a sentence, groups of words need to have at least one independent clause. An independent clause is any group of words that contain both a subject and a verb and can stand on its own."

Example: Some girls in the class.

The fragment can be changed to a correct sentence, as follows:

Some girls in the class study together.

Finally, the reason I am asking: When learning Russian, as a beginner, I sometimes encounter what appear to be sentence fragments. Although it could simply be that I am not sufficiently accustomed to the fact that "to be" or "is" are omitted.

Answer 1

According to Russian Wikipedia (and this is exactly how I remember it from school), the sentence in Russian unlike in English, is not required to have the subject, a predicate or both. We don't call such structures "sentence fragments" and they are considered sentences, though incomplete.

This is from Wikipedia:

If a sentence has all the required sentence members, then it is considered complete. An incomplete sentence is the one which misses formally necessary primary and secondary members, whose meaning is clear from the context or situation. … The incomplete sentences can be missing the subject as well as a predicate at the same time: Where?, Why? [The "where" and "why" here are both sentences, we don't call them "sentence fragments]

Если предложение содержит все необходимые члены предложения, то оно считается полным. Неполным предложением является предложение, в котором отсутствуют формально необходимые главные или второстепенные члены предложения, значение которых ясно из контекста или ситуации[6]. … В неполных предложениях может не быть одновременно как подлежащего, так и сказуемого: Куда? Зачем?

Answer 2

Does Russian have the concept of "sentence fragments" (as English does)?

Yes, it does. This is called ellipsis (эллипсис) and as far as I know it's a thing in every human language.

Is it also clearly considered a grammatical mistake?

It's a rhetorical figure widely used in the language. If used properly, it is not perceived as incorrect by the speakers, despite the fact that its exact meaning is left to the context.

For instance, this famous poem by the Russian author Foeth:

Шёпот, робкое дыханье,
Трели соловья,
Серебро и колыханье
Сонного ручья,
Свет ночной, ночные тени,
Тени без конца,
Ряд волшебных изменений
Милого лица,
В дымных тучках пурпур розы,
Отблеск янтаря,
И лобзания, и слезы,
И заря, заря!..

does not have a single verb in it, but I doubt it can be called "a grammatical mistake".

Answer 3

I don't quite understand the "sentence fragments" thing but in situation when someone asks me "Кто это?", I can safely answer "Какие-то девушки" (no verb, right?). Or, when I'm just sitting on a cliff at a sunset I can tell my girlfriend "Красивый вид" and then kiss her. Even "Красиво" is enough. Actually, any single word can make a sentence in a certain situation.