Book design - Bleed and Trim Size

@adrianbooks  Thank you for reaching out to us. Please follow the suggestions shared by Mike & James. Additionally, you may go to this link to read more about Marks & Bleeds.

Regards,
Vivek 

Trim size is exactly that: the size to which the block of pages will be trimmed to for binding. It's usually within a fraction of an inch of the nominal size, such as 6x9 or 5x8.

Bleed is additional size added to the printing process (plate or digital imaging) to allow printing past the edge of the page, so that when printed and trimmed the image will go right to the edge  —"bleed off" the page, in print terminology.

As Derek says, if you don't have any content, such as graphic lines or thumb tabs or full page art, that is meant to extend to the page edge, you don't need to specify bleeds. There's often a cost associated with bleed printing, even though some providers (Lulu, KDP) just sort of bury it in the final per-copy cost. So make sure you don't specify bleed printing if you don't need it, and prepare to have your job rejected if you do have bleeds and don't spec it. 🙂

For no bleeds, yes, you can set the bleed margin at zero, and when you export to PDF, check the box to "use document settings for bleed."

If no image nor text elements touch the edge of the final trim size, then, no, you do not need to set "bleed". 

Bleed distance (usually 1/8" or 9pt) is defined in the File > Document Setup (or when you began a new document). It is not added to the height and width page size of the book dimensions. It is defined separately, and therefore shows in the .indd document as a red line 1/8" past the black lines that represent the page size (aka the final trim size).