What is a synopsis?
It's a narrative summary of your book--with feeling
The synopsis introduces your main characters and their main conflicts, all woven together in the narrative. (It does not list your characters.) You do not have to include every character or every scene, plot point, or subplot in your synopsis. But your synopsis should give a clear idea as to what your book is about, what characters will care about (or dislike), what is at stake for your heroes, what they stand to lose, and how it all turns out.
It's written in present tense. (reality television of literature)
It's written in third person. (Writing in the third person involves writing as if you are narrating a story)
It's written in the same style of writing your book is written in. One paragraph should flow logically to the next. If you are switching ideas, you need to make sure you build in a transition to connect your paragraphs.
You must put the conclusion to your novel in your synopsis. No cliffhangers or teasers. Agents and editors want to know that you know how to successfully conclude your story.