Jati is a concept closely related to ideas of kinship and lineage. When an individual is born into a jati, they are also born into an ascribed set of social roles and expectations. That said, although a jati may be associated with a unique job - for example, carpenter or priest - not everyone within the jati will perform that job. As well as defining an aspect of that individual’s identity, their jati may provide status and even security.
Historically, there has been fluctuation of ranks and status between jatis. Typically, though, the mobility of the jati on a social scale has been as a group, as opposed to individual social mobility.