Gin is neutral spirit flavored with botanicals, and juniper has to be the loudest one in the room. Take juniper out and you've got vodka with herbs. Keep it in and the rest is a recipe: coriander, citrus peel, angelica, orris, cardamom, whatever the distiller decides.
Every style below is a different recipe for that same idea.
The default. "Dry" means no added sugar after distillation. "London" is a method, not a place, so London Dry can legally be made anywhere.
Flavor: juniper-forward, often with prominent coriander and citrus peel. Crisp, and not subtle. It was the backbone of every gin cocktail until about 2005.
Mid-shelf: Sipsmith, Fords (built specifically for cocktails), Tanqueray No. Ten (citrus-leaning).
Top-shelf: Beefeater 24, Sipsmith VJOP (juniper turned all the way up; makes a killer Martini).
Plymouth
Made only in Plymouth, England, by one distillery. It used to have protected geographic status, which lapsed in 2015. In practice, that one distillery still defines the style. It sits between London Dry and New Western.
Flavor: softer juniper, earthier, a little sweeter, with more root and angelica. Less aggressive than Tanqueray. It drinks rounder.
Use it in: anywhere London Dry feels too sharp. The Gimlet is the classic match, and it's excellent in a Negroni.
What to buy: there's only one, Plymouth Gin. If you make a lot of gin cocktails, the Navy Strength version (57%) is worth owning too.
Old Tom
The historical bridge between malty Genever and bone-dry London Dry: lightly sweetened, sometimes barrel-aged.
Flavor: rounded, softer and maltier than London Dry. The juniper is less aggressive.
Use it in: the Tom Collins (where Old Tom historically makes sense), the Martinez, and any pre-Prohibition recipe that calls for "gin" and tastes weird with London Dry.
What to buy: Hayman's Old Tom, or Ransom Old Tom (barrel-aged, developed with David Wondrich).
Genever
The granddaddy. Dutch in origin, made from a malt-wine base (think distilled beer mash) redistilled with juniper. It's closer to a young whiskey with juniper than to modern gin.
Flavor: malty and grain-forward, with juniper present but not dominant. There are two main styles:
Oude (old): at least 15% malt wine. Traditional and oily. The good stuff.
Jonge (young): leaner and more neutral, a post-WWII style. Skip it unless a recipe specifically calls for it.
Use it in: classic genever cocktails (Improved Holland Gin Cocktail, Holland House). It's also excellent neat or on the rocks.
What to buy: Bols Genever (oude), Old Duff Genever, Boomsma Oude. None are easy to find outside cocktail-focused stores.
Contemporary / New Western
Everything from about 2000 onward that pulls juniper back and pushes other botanicals forward: citrus, cucumber, florals, tea, whatever.
Flavor: all over the map. Monkey 47 piles in 47 botanicals. St. George Botanivore is an herb garden in a glass.
Use it in: the Gin & Tonic is home base, since these gins were designed to play with tonic. Highballs generally. Go carefully in the classics; the Martini section below explains why.
What to buy:
Hendrick's: cucumber and rose, made for G&Ts.
Monkey 47: Black Forest botanicals, dense and expensive. People love it or hate it.
St. George Botanivore: wildly herbal American craft.
Aviation American Gin: softer and citrus-forward, an easy gateway from vodka.
Navy Strength
Not really a separate style. It's usually a London Dry bottled at 57% ABV (114 proof) instead of 40 to 47%. The story goes that navy gunners needed gin that could spill on gunpowder and still ignite. It's almost certainly folklore, and the term itself only dates to the 1990s.
Flavor: the same gin, louder. More juniper, more body.
Use it in: anywhere you want gin to win the fight. Citrus-heavy sours, heavy-tonic G&Ts, a Martini you want to remember tomorrow.
What to buy: Plymouth Navy Strength, Fords Officers' Reserve (a little lower, at 54.5%), Sipsmith VJOP, Hayman's Royal Dock.
Botanicals beyond juniper
The ones that matter:
Coriander seed: citrus and pepper. The second most important botanical after juniper in nearly every gin.
Angelica root: earthy and woody. The "binder" that ties the others together.
Orris root: a fixative. You rarely taste it directly, but it holds aromas in place.
Citrus peel: lemon, orange, grapefruit. The brightness lever.
Cassia / cinnamon: warmth.
Cardamom: increasingly common in contemporary gins, and it can dominate fast.
A juniper-forward gin keeps these in support. A contemporary gin lets them lead.
Why juniper-forward gin makes a better Martini
A Martini is gin, vermouth, and ice. There's nowhere to hide. If your gin's lead note is cucumber or floral water, your Martini tastes like cucumber-floral water with vermouth somewhere in the back.
Juniper has the structural weight to stand up to vermouth's bitterness and the dilution from a long stir. It also pairs naturally with the herbal notes in a good dry vermouth.
Same reason a Negroni made with Hendrick's doesn't quite land. Campari is loud. Hendrick's isn't.
G&T ratios
There's no single right gin-to-tonic ratio. Two that work:
Spanish-style: 1:3 in a giant balloon glass with a lot of ice and a generous citrus garnish. The ice keeps it cold and dilutes slowly. The big glass concentrates aromatics.
British-style: 1:2 in a highball. A shorter pour, more focused.
High-end tonic matters more than high-end gin. Fever-Tree Indian, Fentimans, or any small-batch tonic transforms even a $20 gin. Cheap tonic ruins a $50 one.
Where to go next:Agave Spirits for the herbal and vegetal flip side, Rum Decoded for sugar-based spirits, and Whiskey Decoded once your gin shelf is sorted.