Question about use of "their"

[burkemx]

Hello. Is it accurate that "their" is only to be used to indicate plural possessive (in contrast to singular possessive)?

[Likeguslee]

Their is the possessive form of they, third party plural. Therefore, it should be used only to indicate plural possessive. However, their is not the only plural possessive. We also have our and your, which are the possessive forms of “we” and “you”, first party and second party plural respectively.
Ex: All of our friends’ houses are located in the northern part of the city. We met your parents at a party the other day. Their jobs are very stressful.

[burkemx]

Thank you!

[MrPedantic]

Hello BMX

Additionally, "their" is commonly used instead of "his or her", where the gender is inclusive or uncertain, e.g.

1. A person can't help their birth. (Thackeray)
2. It's enough to drive anyone out of their senses. (Shaw)

This usage is regarded as ungrammatical by some. It's probably best avoided in a situation where your grammar may be under scrutiny (e.g. in an exam or job application).

MrP