Perhaps you meant one of the following:
* VOD (Video on Demand): This refers to a system of watching videos or movies at any time you choose, like Netflix or Amazon Prime. This isn't related to essays.
* A specific type of essay: There are many different types of essays (e.g., argumentative, persuasive, narrative, expository). Perhaps you heard a term that sounds similar to "vod"?
* A misspelling: It's possible you're thinking of a term that is spelled differently.
Could you please clarify what you meant by "vod essay"? I'd be happy to help you understand it.