What is a reason for using VLANs in an IP network?

 A reason for using VLANs in an IP network is to isolate hosts within the same IP subnet. VLANs (Virtual LANs) are logical grouping of devices in the same broadcast domain. VLANs are usually configured on switches by placing some interfaces into one broadcast domain and some interfaces into another. Each VLAN acts as a subgroup of the switch ports in an Ethernet LAN. VLANs allow network administrators to group hosts together even if the hosts are not directly connected to the same network switch. By using VLANs, hosts within the same IP subnet can be separated into different broadcast domains, which enhances security, reduces network congestion, and simplifies network management78.

References: 8 Different Types of VLANs in TCP/IP Networks, What is a VLAN? - Study-CCNA