Cinnamon, the spice, is the dried bark of an evergreen tree, the cinnamon tree (Cinnamomum zeylanicum), that belongs to the laurel family. The tree is native to the warmer regions of Asia, but is now planted throughout the tropics. In southern China, a sibling, the Cinnamomum cassia, is also used to produce cinnamon. It is obtained by scraping the outer bark off branches and then to mistreat the branches to loosen the bark. This dried inner bark curls and that's our product.
The first part of the scientific name, Cinnamomum, obviously has the same origins as the English name. Because cinnamon has been traded by Arab merchants since time immemorial, the word also has a long history: the Ancient Greeks borrowed their word kinnamomum from the old Hebrew word kinamom and the Aramese qunimom. At the end of its jouney it may even be connected to the modern Indonesian word kaya manis (‘sweet wood’). The second part, zeylanicum, is the Latin version of Ceylon, modernday Sri Lanka. Cassia, the name of the related species, originated via the Greek kasia from the Hebrew words q'tsi-ah and qatsa, which used to mean 'truncate, stripping (of the bark)'.
Most people really do like the smell and taste of cinnamon. Its pervading smell and taste is the result of a aromatic essential oil called cinnamaldehyde. Other important ingredients and thus also in its oil are ethyl cinnamate, anethole and eugenol.
It has been suggested that it would be a very good insect repellent and, yes, cinnamon oil really is extremely effective to destroy the larvae of bothersome mosquitoes. The observant reader will notice at this point that, if cinnamon oil is able to kill mosquito larvae, that it must have some unhealthy properties. Well, that attentive reader is right.
Although it still needs a lot of additional research, it appears that it might help in the treatment of diabetes II. It has properties that lowers the blood sugar levels and helps to lower the level of the glucose after food intake. However, at this moment the scientific results are still mixed. Regarding the possible link between cinnamon and diabetes it was concluded  that, out of the ten published studies, only two could withstand the academic scrutiny. The inescapable conclusion was therefore that there was insufficient evidence to support the link between the product and diabetes type 1 and 2.
 Leach et al: Cinnamon for diabetes mellitus in Cochrane Database of Systematic Reviews - 2012
See also: https://www.naturalspices.com/ceylon-cinnamon-ground.html