It's a tough fact of life as an aspiring writer that often a submission gets no further than the bin or the delete button on an agent's computer.
In fact there are certain ways of writing a synopsis that guarantee I will reject a submission point-blank. A synopsis is NOT like the blurb on the back of a published book. If you send in a short paragraph that says something like 'Amelia never knew how much her life meant to her, until she was on the verge of losing it!' and leave it at that, that tells me - the professional reader - nothing about the plot, and is therefore unhelpful.
A synopsis should include the whole of the plot. Do not leave out any twists or turns - the reader (me, an agent, an editor) is using it to assess the plot. To do this efficiently, we need all of it.
Having said that, a synopsis needn't include all the sub-plots - it's good to give an idea of what happens, but not a blow-by-blow chapter breakdown. A synopsis is not another chapter for your novel. It should be no longer than about one side of A4 - but it can be single-spaced.
It's not necessary to put each character's name in capitals or to add a sheet about characters either. The entire purpose of a synopsis is to summarise the plot. It's not a marketing tool, part of your covering letter, or part of your novel or book.
To get practice at writing yours, why not try writing a synopsis of a classic - or of a book you've just finished reading - and check if it meets the criteria above!
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