In Indian railways, we can identify unreserved coaches as UR name which means Un-reserved
UR coaches has middle door, whereas normal reservation compartment do not have middle door.
In Ur coach there won't be any middle berth or side upper berth which is different from reservation compartment especially Non AC and AC Sleeper coach.
The upper berth is also a typical luggage rack, but people sleeping and sitting on that is a very common scene.
There is no passage to the Sleeper or AC coaches because the connecting doors are locked to prevent unauthorised entry.
UR coach is commonly seen at Front side after EOG Generator Car or SLR cum coach or back side. So passenger have to walk little distance to reach there.
But here twist is nowadays Indian railways adding 2S second sitting coaches D1 coaches as UR coach especially LHB Coaches, intercity express or slower express train (day time).
Many passengers assume this coach is reserved, but that’s not always the case. Check carefully whether it is a D1 reserved coach or a UR (Unreserved) coach.
There is no reservation needed to get seat,,you are free to sit anywhere.