Most people simplify asexuality and the asexual spectrum into 3 groups: asexual, demisexual, and grey-asexual.
Asexual is just what I defined in my first post, so don't think I went and lied to you. This spectrum simply comes from not seeing just anyone as sexually attractive. Since you know already a little bit about asexuality, I'll focus more on demisexuality and grey-asexuality. I am not as knowledgeable in this area, however, so please forgive me for any errors.
Demisexuals can and do feel sexual attraction. They simply need a stronger bond before they feel it. This bond as I understand can be romantic or platonic, but it needs to be there for that attraction to occur. They can be considered asexual because until that bond forms, they don't experience sexual attraction, same as an asexual. (There are also demiromantics, as well. This follows the same principle except there needs to be a platonic bond before they feel romantically inclined. Oh, and there is also such a thing as being aromantic. Nearly forgot to mention that.)
Grey-aces fall between asexuality and other sexual attractions. It is possible that they may only experience sexual attraction in certain situations, or may have those attractions but feel no need to act on them. Really, I have no idea what I can list here without generalizing. It's different from grey-a to grey-a. And grey-romantics, as far as I am aware, are also a possibility.
Thought I'd give a few examples from the spectrum to show how diverse asexuals are. There are smaller categories, as well, but then I could go on forever and still miss something, so these are the main three. Just in case you were interested.
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