Query Letters are often the first thing a publisher sees when receiving your manuscript. Make it short, sweet, and enticing so that he or she will want to read more. The ideal query letter sells both your manuscript and you yourself as an author.
Your synopsis is a short summary of your manuscript, including the ending (this is not the time to "tease"). Your outline may be very helpful here, as well as your plot circle and understanding of the three-act structure (help with all of these is available in the Developmental Editing section).
Understanding submission guidelines is important! We can help with that.
Children's/Picture/Chapter Books: $1/page
Middle Grade/Young Adult Books: $5/page