What is a Bullet Essay? 
A "Bullet Essay" is a one-page set of single-sentence statements referred to as bullets about a given topic. 
A form of journal essay, bullet essays are used to draw out further articulation of ideas and creative objectives.  A bullet essay tends to work from an overview and become more specific down the page.  The first Checkpoint Exercise in our Pro Membership materials is the Concept Bullet Essay, sort of the granddad of all bullet essays, which is the only one with a specific set of questions to answer.  Past Pro Members will be interested to know that it is in effect the evolution and refinement of the old 18-Question Project Plan.  All other Bullet Essays, including thematic, genre, style, character level, project comparison, comedy, drama, and a myriad of others, are more free-flowing explorations.  Of course, the goal is to lead yourself to make a point.
In the Writers Boot Camp lexicon and format, a "bullet" is a single-sentence statement, preceded by two hyphens.  By definition, a single sentence may contain only one period--and if there happens to be a second, then that represents a second sentence, even if you see it as just a fragment, or if you happened to write it because you were simply riffing.  Even with that admonition to keep it to a single sentence, it can be three lines down the page though, again, only one single sentence.  Remember, that a Premise Line, which is also only a single sentence, can still be up to 50 words and yet be considered compact enough to fulfill the goal of economy.
A bullet starts with a double hyphen (--) without any additional spaces before the first letter of the sentence.  The hyphens, perhaps the equivalent of a "bullet", are completely flush with the left margin of the page or email box--and then after each sentence, a return to provide greater readability.  These hyphens are much different than the format options used in Microsoft Word.  In Word, the format options automatically indent and take up too much space on the page.
These format expectations and guidelines may seem restrictive, though they are intended to be very streamlined and allude to many of the challenges of getting screenplay format to become second nature, accordingly, as well as achieving other higher standards of expression.  When judiciously keeping your thought/statement to one sentence it will naturally push you to make sure it is clear and compact.  The emphasis is not necessarily on brevity but on economy.  You can read compact to mean that in focused space you can feel assured that you haven't left anything out.  The secret to the effectiveness of a sentence is usually the writer's effort to test the second half of each sentence to make it as explicit as possible without being too detailed per the level of expression.  
Think about the vaguely expressed impact and detail of the following sentence:  "Jack and Jill go up the hill to fetch a pail of water. "  In effect, structurally, it's difficult to ascertain from its content whether it's meant to represent the entire story or only one scene or sequence.  In essence, it's barely a set-up for either.  Why are they there, how long does it take, how do they interact, feel about each other, do they make it up the hill and what happens once arrived at the summit?  It would be much stronger for the writer to have provided the details of its second half.
To quote JG, "Concision forces decision".  When you imagine the nature of prose writing, a bullet essay helps foster more compact writing when the bullets are later grouped together into paragraph form.  The ultimate creative goal and impact of a bullet essay is to achieve greater clarity and focus with less tangential material.  For example, if each writer were to write a One-Page Summary of their story at the start of Basic Training after the first night of session, routinely their prose essay down the single page would be poorly structured.  Knowing more about the beginning of their story at the start of the writing process, it would be common by two thirds to three quarters the length down the page, their prose would still reflect the 1st Act of the story, mostly the set-up.  But in a one-page expression of a story, say four paragraphs, each paragraph representing 30 pages structurally, the beginning would, could, and should naturally end at the end of the first paragraph.  This disappointing phenomenon exhibited by newer writers is the reason we focus on so many single sentence exercises, not only for the sake of enhanced structure but also for more unity of conceptual entertainment.
For the New York Bullet Essay Alumni Contest in February 2021, here's an example of a few bullets and how a Bullet Essay might start:
--Jeff Gordon's favorite restaurants in Soho are Raoul's on Prince Street--between Sullivan and Thompson--and Blue Ribbon Brasserie on Sullivan, just north of Spring Street.
--When JG stays in the City, he'll usually meet friends and alumni at Raoul's after a speaking event for the steak au poivre with fries and a vodka martini.
--Not that he can stay up very late at night anymore, it's still great to know that Blue Ribbon serves fried chicken until 3am, or possibly even later.

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