Communal marketing is like when you and your friends decide what toys to play with. Let's say you have a cool toy and your friend has a fun toy too, but you both really want to play with both toys. So, you both agree to share your toys and play together.
Communal marketing is kind of like that, but with businesses. Sometimes, businesses might have something really cool that they want to advertise, but they don't have enough money to advertise it all by themselves. So, they team up with other businesses who have cool things to advertise too. Together they can pool their money and create a bigger advertising campaign that will reach more people.
It's like your friend and you sharing your toys, but instead, it's businesses sharing their advertising money to get their products or services seen by more people. By doing this, they can reach a bigger audience and have a better chance of selling their stuff.