let's go deeper into the essence of gin

Image from Wikipedia Commons

Gin is the distillate of a grain mash with various flavouring agents. For flavour, there is one compulsory ingredient, which gives the recognizable flavour and defines what gin is: Juniper berries.

These flavouring agents define gin, not the base material. Gin can be made with any fermentable ingredients, like vodka. If vodka is infused with juniper, it becomes gin.
The more or less sophisticated way the different ingredients will be integrated in the spirit will define the quality.

The botanicals come from all over the world for instance Cardamom often come from Sri Lanka, Cassia bark from Vietnam, Orange peel from Spain, Coriander seed from the Czech Republic, Angelica root from Germany. Most of the Juniper berries themselves are imported from Italy but some American Gins use local varieties.
 
Some components and what they bring to the wedding:
Juniper* gives the characteristic pine-like, heather, lavender notes
Coriander seeds bring spicy notes, sometimes peppery (if coming from Morocco), more citric and/or floral if it comes from East Europe (especially from the Czech republic)
Angelica roots brings musky, earthy, dry aromas.
Orris roots provide the final alcohol with earthy, violets aromas. It is also used as they have the capacity to hold volatile flavour compounds.
Speaking of which, dried citrus peels brings a certain zestyness and freshness. It is the most delicate flavour to capture, as it is highly volatile. This is the first component to evaporate during distillation process, after the heads. Temperature must not be too high if citrus peels are used.
Dried orange peels are known for bringing an intense slightly bitter edge
Cinnamon and cassia bark often bring sweet tropical note.
Bitter or sweet almonds convey a marzipan hint.
Liquorice gives a perception of sweetness, which softens the juniper
Many other ingredients can be used like nutmeg, caraway; actually, the whole range of worldwide available botanicals/fruits can be used.
 
See Monkey 47 and its … 47 ingredients.

Image found on the Monkey 47 website

more about the juniper berries …

*There are many Juniper subspecies and this is also a very old plant: it already grew on the continent that preceded the separation into the continents as we know them now, this is why juniper can be found in Europe, Asia, Americas.

The berries grow on a small tree that can live up to 200 years. The trees are either male or female. The pollen from a male tree must cross a female tree, thank you wind & flowers. Once pollinated the berries take 2 or 3 years to mature. Harvesting is not easy as the berries mature differently on the same branch, up to three years of maturation at different steps can be on the same branch. For that reason it is hard to industrialise the harvest, which make it labor and cost intensive. After harvest the berries are let to dry in a cool dark place to prevent the berries to loose their flagrance.

Please note : not all juniper are suitable for gin making, some are actually toxic (like Juniper ASHEI or Juniper SABINA)