Some VLAN-related nuggets that you may find useful for your post/blog:

• 99% of the time when people refer to VLAN, they’re talking about 802.1Q (VLAN tagging). There are others, so it’s up whether you want to cover those as well.
• The word “Trunk” can mean different things, depending on vendor. In the Cisco world, it means a line/port carrying multiple VLANs. With many other vendors, such as Aruba/HPE, it refers to link aggregation which isn’t necessarily relevant to VLANs
• A lot of hardware still use VLANs even none have been configured. For example, defaulting all switch ports to have an Access tag of 1 makes it behave like a dumb switch. This can cause issues later if you’re configuring VLANs elsewhere
• Anything connected to a VLAN-enabled switch will have to be connected to a port with a default VLAN tag. This is usually referred to as an “Access port” or an “Untagged port”
• “How do I configure the switch to allow units on VLAN 123 to talk to VLAN 321?”. You don’t. Connect both VLANs to a router which will route between them. Either connect the router to both VLANs individually and skip the tagging on the router, or you can run a single trunk between the switch and the router which carries both VLANs. The latter requires you to configure VLANs on your router accordingly.
• It might make sense in many cases to have the VLAN tag the same as the last octet in the IPv4 subnet. Makes it easier to keep track of.
• A PC can implement VLANs on its network port, allowing you to connect to a trunk port and access several VLANs with one cable.

Source: VLANs have been an integral part of my career for 20ish years.