хотя

The conjunction хотя is the standard way to express concession in Russian. It is used to present a 'counter-expectation': Fact A is true, but Fact B happens anyway.

1. Sentence Structure
When хотя introduces a full clause, it can be placed before or after the main clause. A comma is always required to separate these clauses.

• Хотя шёл дождь, мы пошли гулять. (Although it was raining, we went for a walk.)
• Мы пошли гулять, хотя шёл дождь. (We went for a walk, although it was raining.)

2. Informal and Formal Variants
In spoken Russian, the shortened form хоть is very common. It functions identically to хотя when used as a conjunction meaning 'although'. To express 'at least', Russian uses хотя бы or the colloquial хоть (e.g., дай мне хотя бы один шанс / дай мне хоть один шанс). While хотя alone can historically or colloquially mean 'at least', modern standard Russian strongly prefers хотя бы or хоть for this meaning. Furthermore, хотя бы can also mean 'even if', in which case it requires the verb to be in the past tense (subjunctive mood), similar to 'если бы' (e.g., Я не сдамся, хотя бы мне пришлось умереть.). In formal writing, the complex conjunction несмотря на то что is often preferred. Note that this phrase is often treated as a single unit without an internal comma, especially when it begins a sentence.

3. Conversational Nuance: (А) хотя...
In natural speech, you will often hear Хотя... at the beginning of a sentence. This is used to mean 'Actually...' or 'On second thought...', signaling that the speaker is reconsidering what they just said. You may also hear А хотя..., where А is simply an optional conversational filler. Important punctuation note: хотя is never followed by a comma (unless an interrupting subordinate clause immediately follows), even when used at the beginning of a sentence to mean 'Actually...' or 'On second thought...'. Placing a comma after it is a very common mistake.

4. Correlative Words
In the main clause, хотя is often paired with но (but), всё-таки (nevertheless), or всё равно (all the same) for extra emphasis. The combination хотя (и)... но... is a perfectly grammatical and standard double conjunction in both formal and informal Russian. When this combination connects single words (homogeneous members) rather than full clauses, a comma is placed only before но, not before хотя. However, when хотя connects single words without но, a comma is always required before хотя because it acts as a simple adversative conjunction (e.g., Фильм был старый, хотя (и) интересный.).

5. Emphasized Concession (хотя и)
The particle и is frequently added to хотя (forming хотя и) to add emphasis to the concession. Note that the и here is an emphatic particle and should be left completely untranslated in English (do not translate it as 'and'). This can be used with full verbs as well as with adjectives or adverbs in reduced clauses.

• Хотя он и знал правду, он ничего не сказал. (Even though he knew the truth, he said nothing.)
• Фильм был хотя и старый, но интересный. (The film was, although old, interesting.)

6. Mood and Tense
Unlike some other languages, хотя does not require a special mood. You simply use the imperfective or perfective indicative (past, present, or future) as the context requires.