они + -ют/-ут/-ят/-ат

In Russian, the third-person plural is used when the subject is они (they) or a plural noun.

1. First Conjugation (Type I):
Most verbs ending in -ать, -ять, -еть, -нуть, -ти, or -чь use these endings:

• -ют: Used after vowels and soft signs (or soft consonants). Examples: читают (they read), пьют (they drink).
• -ут: Used after consonants (Example: идут - they go). Note that the stem consonant sometimes changes (mutates) before these endings (e.g., писать -> пишут). The 8-letter spelling rule (г, к, х, ж, ч, ш, щ, ц) ensures that verbs with stems ending in soft hushing consonants (like ч or щ) take -ут instead of -ют (e.g., плакать -> плачут).
• -овать / -евать verbs: Verbs ending in -овать or -евать replace -ова-/-ева- with -у- or -ю- before adding the ending. Example: танцевать (to dance) -> они танцуют.

2. Second Conjugation (Type II):
Most verbs ending in -ить use these endings:

• -ят: The standard ending. Example: говорят (they speak).
• -ат: Used after sibilants (ж, ч, ш, щ) because of the 8-letter spelling rule (г, к, х, ж, ч, ш, щ, ц). Example: учат (they teach).

Note that unlike Type I verbs, Type II verbs never undergo consonant mutation in the они form. Mutation only happens in the я form. For example, сидеть (to sit) becomes я сижу, but remains они сидят (not сижат).

3. Important Exceptions:
There are 11 common verbs ending in -ать (like слышать, дышать) and -еть (like смотреть, видеть) that actually follow Type II rules, meaning they take the -ят or -ат endings (e.g., они смотрят, они слышат). Conversely, the verbs брить (to shave) and стелить (to lay/spread) end in -ить but follow Type I rules, taking Type I endings (они бреют, они стелют). Additionally, some verbs are irregular, such as хотеть (они хотят) and бежать (они бегут).

4. Reflexive Verbs:
When a verb is reflexive, the suffix -ся is added after the plural ending. In this form, it is always -ся (never -сь). Note that the combination of the -т ending and the -ся suffix (-тся) is pronounced as -ца (/tsa/).

• Example: они учатся (they study).
• Example: они смеются (they laugh).

5. Stress Rule:
As a helpful rule of thumb, for regular verbs with shifting stress, the stress falls on the ending in the я form, but shifts to the stem in all other forms, including они. Therefore, the stress in the они form matches the stress of the ты, он/она, мы, and вы forms. However, some irregular verbs break this rule (e.g., хотеть: ты хочешь / они хотят; есть: ты ешь / они едят; дать: ты дашь / они дадут). Additionally, when the endings -ят and -ат are unstressed (e.g., видят, смотрят), the vowel reduces and sounds closer to an 'и' or a schwa.

6. Special Functions:
This form is also used for:

• Naming: Как их зовут? (What are their names?)
• Impersonal 'They': When referring to 'people in general', the pronoun они is typically omitted. Example: Говорят, что... (They say that...).
• Forming Participles: The они form serves as the foundational stem for creating present active participles in -ущий/-ющий and -ащий/-ящий. By dropping the -т and adding -щий (e.g., читают -> читающий), you can form these adjectives. Becoming comfortable with the они form is important for building fluency in these advanced structures later on.