Question : Problem: vlans

I noticed the other day when backing up the configuration of a few switches on the network that the switches in the remote offices had a different name/number for accessing the LAN
here is what i mean.....at the main office i have a vlan created called VLAN 25 for access to the lan with an ip address of 192.168.10.5 255.255.255.0 on the vlan
At all the remote office i have switches with vlans on them for various reasons but the vlan that is setup on the other switches in the other remote offices i assumed had VLAN 25 on them for LAN access but instead some switches are using VLAN 1 or VLAN 7 for example for LAN access
Both the VLAN's in question have an ip address from the proper subnet 192.168.10.8 255.255.255.0 for example and i am able to get lan access when plugged into one of the switches that has the proper vlan access to it but
I assumed that all the vlan identifiers had to be the same throughtout your network,: for example:   for LAN access on all switches:    setting up VLAN 25 on all switches rather than the structure that is currently in place and working
I am assuming that the reason it works it that whatever number was used or created on the switch it works because it is given an ip address from the LAN Subnet

Can someone clarify why this is working this way? the proper way to do it?
Because i thought the say i wanted to designate VLAN 25 for LAN access throught out my network that vlan 25 had to appear at every switch where i need LAN access but that is evidently not the case?

thanks

Answer : Problem: vlans

The only time the VLAN number have to match is when you have trunks established between the switches.

If you don't have trunks, then the VLAN numbers don't HAVE to match. But as you're seeing, it makes things a bit confusing. Most people would keep them the same and avoid the possible confusion.