I think you will find all the information you search for in this book (there are plenty out there on the subject).
Anyway in brief terms inflammation is a reaction of the body to a deleterious event (eg too hot, too cold, dangerous chemicals, radiation, toxins etc) that could happen on a small (cellular level), or large scale (organ level) and in a little (a paper cut), or long time (chronic diseases) and provokes cellular damage.
It involves a cellular and humoral response but it's really a big issue, difficult to solve in just a post.
The invisible inflammation you mentioned falls in this field, but it depends on the specific subject since inflammation is involved in practically all the human diseases.
An example
Hope it helps
EDIT
i changed the second link since it was not freely available to everyone.
toxins
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