Identity
An identity is a set of most of than not self-imposed rules that decide over your whole being. It is noteworthy that an identity is a purely social thing; people living in social isolation tend to have less identity than those with a rich social life, as such the less social you are, the less value an identity has for you.
The more you have of an identity, the more rules you have to abide by, as seen on anonymous message boards, where people have no hard-coded identity, and just let their ideas and thoughts flow (at least ideally), and the polar opposite being social media, wherein people have very elaborate identities, and thus also abide by more rules.
People with an identity often times ask themselves whether doing or saying something suits their identity, rather than just saying what they think, because they want social approval by people with the same identity.
In social situations an identity is an "compatibility check" of sorts when deciding who to sort out of a social group.
All identities are retarded, and it's remarkable how people try to search for some meaningful identity, and in particular the more politically reactionary people explaining that modern identities are not worthwhile, and one should resort to having biological imperatives and other hard-set attributes of oneself as an identity, meanwhile what progressive politics suggest is that one should be free to form an identity from whatever one likes, more so with freely chosen parts of one being. However, both are equally retarded, as you shouldn't limit yourself with identity issues at all, and rather just let your thoughts flow as they come.
"Finding yourself" is an euphemism for finding boundaries to follow.
For many their occupation is a big source for establishing identity, however this seems to be more true for the Baby Boomer and X generation rather than for more recent generations. In TV shows, which are mostly consumed by old people, one of the first question asked if a new person appears or is selected is what kind of job they have, because work is not only a way to establish your own identity, but also to sort people into certain categories - categories of identity.
Culture just means collective identity, and as such is equally, if not more harmful. This gets even more clear when seeing what happens if you don't follow culture: You get ostracized, bullied, and disregarded. This applies to subcultures to the same degree it does to the culture of a country, region, or religion.