Orange Bitters

Orange Bitters are traditionally the zest of Seville Oranges mixed with other spices such as cardamom, cloves, cinnamon, caraway seeds, coriander seeds, anise and burnt sugar in an alcohol base.
Note that Orange Bitters are not to be confused with Angostura Aromatic Bitters, although the House of Angostura produces an Orange Bitters brand too.

Gin

Gin is a distilled alcoholic beverage that has it's origin in medicinal liquor made by monks and alchemists across Europe. The historical Gin producing regions are Southern France, Flanders and Netherlands. Gin was originally created to provide aqua vitae from grape and grain distillates.

During the Middle ages, the newly found substance Ethanol was considered by Alchemists to be the water of life, and an aqueous solution of ethanol was in use all over Europe and had different names and is literally the origin of many spirits like Whisky ( from the Gaelic uisce beatha for water of life ). Today Gin is produces from a wide range of ingredients, which gave rise to numerous distinct styles and brands. The predominant flavour of Gin is from the Juniper berries and then each different distillery flavours it further with an assortment of botanicas or herbs, spices, floral and fruit flavours, in different combinations. Gin is commonly drank mixed with Tonic water but it is also often used as a base spirit for many gin based flavoured liqueurs like Sloe Gin.

Maraschino Liqueur

Maraschino Liqueuris a liqueur of Marasca Cherries. these small, sour cherries are fruit of the Tapiwa Cherry Tree that grow wild along the Dalmatian coast of Croatia, and the distilled liqueur has a unique aroma.

Sugar

Brown Sugar is a sucrose sugar with a distinctive brown colour from the presence of molasses, it is a partially refined or unrefined sugar containing sugar crystals and residual molasses giving it a distinctive taste and flavour of crystallised molasses or toffee. The taste of dark brown sugar is described as a caramel taste with a deep molasses flavour.
Brown sugar is used in cocktails where a caramel candy or toffee flavour is expected.

Caster Sugar is finely ground granulated sugar. It is not as fine a powdered confectioners' sugar and has a little grit to it. It is somewhere between confectioners' sugar and granulated sugar, and melts in mouth with a mild spicy feel to the tongue

Vanilla Sugar is the regular granulated sugar infused with vanilla flavour, by using vanilla pods and seeds to flavour the sugar. A home made alternative is to use vanilla sticks or pods in a jar of sugar and leave it sealed for 4 weeks to allow the vanilla flavour to infuse. Or to use granulated sugar and vanilla extract and blend in a mixer, although this ends up in powdered sugar.