We know that a switch can be divided logically into different lans by using VLAN using VLAN tagged mechanism.
VLAN tagging is not required to logically divide a switch into different LANs. VLAN tagging is only necessary when sending data from more than one VLAN on the switch to another switch or device over a single link.
Now is it necessary that in each vlan to tagg a port?
No, as I said above, it is only necessary when you are sending data from more than one VLAN across a single link.
Also what is the use of tagged port?
By now, you can probably guess where this answer is heading. The use of a tagged port (aka trunk port for some vendors) is to allow you to send the data from more than one VLAN over a single link. The tagging allows the receiving device to understand which traffic belongs to which VLAN allowing it to maintain the logical separation.
For normal access ports, there should only be one (untagged) VLAN configured and no addition (tagged) VLANs.