Being able to identify different parts of a hook is critical to the fly tying process, both in terms of material placement and proportions.
The eye of the hook, to which you attach the tippet of your leader, is located at the very front end of the hook shank. Some are downturned like this, others flat or ringed and still others turned up.
The shank of the hook usually begins right behind the eye, and extends all the way back to where the hook begins to bend.
The start of the bend begins at the back end of the relatively flat hook shank.
The bend is basically the curved part of the hook.
From the front edge of the hook eye to the back edge of the bend represents the entire hook length.
The barb of the hook is located forward of the bend and just rearward of the hook point.
The hook gap or gape describes the distance between the hook shank and the point.
The throat is the distance between the furthest point back on the hook bend and the hook point.
Understanding hook anatomy and terminology is a good first step to becoming an accomplished fly tier.