The straight-leg jean is a timeless choice with a classic fit from hip to ankle. “Jeans are now, without a doubt, the anchor of the modern man’s everyday wardrobe,” says Erik Torstensson, co-founder of Los Angeles-based brand FRAME. “From the office to a nice dinner, or a day spent at home, we ask a lot from our jeans, so it is important to purchase jeans with versatility.”

Since a straight leg can range in leg width, this fit is fairly adaptable for most intents and purposes. Just make sure it fits well around your top half, without too much excess denim at the rear.

This style sits comfortably between the extremes of regular and skinny cuts. Some slim fits taper towards the bottom or can be cropped. You’ll find that a good-quality pair of slim-fit indigo jeans will partner well with anything, whether that’s a tailored jacket, a chunky-knit sweater or just a crisp white T-shirt, sneakers or leather loafers.”

Wide-leg jeans are exactly that – a voluminous straight-cut leg without the shape of flares. In terms of comfort, you’d be hard-pressed to do better. A good rule of thumb is to balance out the volume with slimmer pieces; say, a merino-wool rollneck or a slim-fitting crew-neck T-shirt and short trucker jacket, perhaps. Need help styling your baggy jeans? We’ve got you.

Unfairly usurped by skinny and slim styles for a long while, wide-leg, baggy and flared jeans are truly back in the game. Flares are so named because they flare out from the knee (wider than their slimmer cousin, the boot-cut jean). These jeans have more than a hint of the 1970s about them, and, as such, often come with a high-rise waist. The combination provides a long, elegant silhouette. Pair with a cropped bomber and vest, or loosely tucked wide-collar shirt.

This term refers to the length from the crotch to the waistband – basically, where the waistline of the jeans sits. This varies from 7 to 12 inches. With a low rise, the waistband will sit below the navel, whereas a high rise will sit above it. High-rise jeans are generally better suited to taller men, while low rises are a good option for the less lofty. A regular rise is worn at the natural waist.

Denim

We’re stating the obvious, but jeans just wouldn’t be jeans without denim. The fabric is made using a diagonal-weave technique, which makes it extremely hardy. Testament to this durability is a pair of Levi’s that were discovered in an abandoned Nevada gold mine in 1998. Despite dating from the 1880s, they had only a few nicks and scrapes and were still wearable.

“Denim is about character,” says Martin Gustavsson, head designer of Swedish label Nudie Jeans. “It should have a visual and physical depth. To me, what makes great denim is balance – the balance between yarn thickness, eventual irregularities and weave density. It’s like the balance of a grounded personality; a person who has enough character to make their voice heard without dominating the entire room.”

Dry denim

Also known as raw or unwashed denim, it has a deep indigo colour because it does not undergo any washing after dyeing. Jeans made from this denim are fairly stiff and the wearer has to break them in. Their naturally dark hue makes these jeans a great all-rounder that will work with almost everything, from tailoring to T-shirts and sweatshirts.

Twill

Twill is a material with a diagonal weave and, yes, denim is a type of twill. Most denim has a right-hand twill, which means the diagonal lines rise from left to right. Left-hand twill runs in the opposite direction and has a softer feel, which makes it prized by some aficionados.

Ring-spun denim

This was used in jeans up until the 1970s, but has enjoyed a revival among denimheads in recent years. The process involves twisting the cotton fibres by spinning them using a ring, which creates a stronger, softer fabric than open-end denim, which is more commonly used in commercial production. It has the more characterful, uneven appearance associated with vintage denim.

Open-end denim

First introduced in the 1970s, the process involves mock-twisting the cotton fibres by blowing them together. It results in a bulkier, slightly coarser, darker fabric because it absorbs more dye.

Selvedge

This refers to the edge of the denim fabric, which is usually stitched with a coloured thread that prevents the denim from unravelling and provides a neat, clean finish. It was originally woven on narrow 29-inch looms before manufacturers switched to more efficient 58-inch and 62-inch looms. With the selvedge revival, these old looms have been dusted off and put back into service.

Japanese denim

The Japanese are regarded as the guardians of selvedge denim – and with good reason. Woven on traditional Toyoda looms from quality ring-spun yarn and specialist cotton blends, it undergoes several baths in natural indigo – a 1,000-year-old practice known as aizome. The end result is ultra-durable denim, with a darker, richer shade that fades with greater character over time.

Stretch denim

This denim has a small percentage of elastane added to offer greater flexibility and comfort. It was first introduced in the 1960s.

Weight

Denim was and still is graded by its weight per yard of fabric with a 29-inch width. The first denim was 9oz and has gradually increased in weight over time. Modern denim tends to be 14oz, which is thicker and more durable. Mid-weight denim offers a longer lifespan than lightweight styles, plus it has year-round wearability, unlike heavyweight denim.

Indigo

The natural dye originally used to colour denim, derived from the Indigofera tinctoria plant. In 1897, the chemical structure was analysed by German chemist Adolf Baeyer and synthesised, and this is what most manufacturers use today. Pre-1920s jeans were all dyed with natural indigo and had a paler, greener cast. The best kind of indigo dyeing is rope-dyeing, where the yarns are twisted into rope before being dipped into the indigo dye. This means the fibres are not fully penetrated by the dye, which allows the denim to develop a desirable faded patina with age.

Dip-dye

The traditional method of dyeing the cotton yarn used to make denim. It’s normally dipped into an indigo-dye bath between six and eight times.

Double or over-dyeing

Traditionally, over-dyeing meant the denim was woven from yarn dipped in an indigo dye bath 12 to 16 times, instead of the standard six to eight. This creates a deeper, richer shade of blue. The same effect can also be achieved by adding a higher concentration of indigo in the dyeing process.

Enzyme wash

This is a technique that softens the fabric and emphasises highlights. The enzymes used are organic matter that speed up natural reactions. The enzymes eat the cellulose in the fabric, which makes it feel soft.

Stone wash

Originally, this process involved washing the jeans with pumice stones, which would give the fabric a worn-in look, and was allegedly invented by the Hollywood western wear consultant Nudie Cohn in 1960. Today, the effect is achieved by using enzymes – the original process isn’t particularly eco-friendly.

Acid wash

This was a defining feature of 1980s denim and is becoming popular again. It used to be achieved using pumice stones soaked in chlorine bleach to create irregular bleached-out patches in the fabric.

Distressing

Worn-in, seasoned effects achieved by the use of chemicals and enzymes, washing and abrasion.

Garment-dyeing

The usual practice of dyeing involves colouring yarns before they are woven into cloth. With garment dyeing, as the name suggests, dyeing is done after the item has been made. This provides a consistent shade throughout the garment. Indicators include pocket linings or labels that are dyed the same colour as the fabric itself.

Coating

Coatings are applied using pigment or acrylics, depending on the desired effect. They are often used to prevent fading and staining of the denim and result in a leather-like sheen.

Tobacco stitching

The brown stitching that is one of the distinguishing features of denim.

Double stitching

This dual stitch is achieved by using two parallel needles simultaneously and adds strength to the jeans.

Chain stitching

The traditional stitch used to make jeans, which can only be achieved with a vintage Union Special sewing machine. In chain stitch, a single thread is looped over itself, which means it looks like a continuous, rather than a dotted, line. Chain stitching also causes roping (see below).

Roping

This term is commonly used to describe the crinkled effect you get on the hem of a pair of jeans when they have been chain stitched with a Union Special sewing machine. It can also refer to a different hem detail, when a thin piece of rope is sewn inside a pocket edge, both reinforcing it and resulting in a more textured fade.

Rivets

These little metal fastenings reinforce jeans at stress points. Jacob Davis, a Nevada tailor, first introduced them after miners complained that the weight of gold nuggets caused their pockets to rip.

Whiskers

These are creases impressed on the front of jeans that resemble whiskers. They’re also known as buffies, which is derived from baffi, the Italian word for moustache.

Five pockets

This is a quintessential feature of the classic jean – two pockets in front, two at the back, and a coin pocket inside the right front pocket. Originally, the fifth pocket was on the thigh and used as a tool holder.

Zip and buttons

Committed denim snobs often get into heated debates about which is better. Buttons predate the zip and are more “authentic”, but zips are far more practical. What is important is the quality of the hardware. “Make sure the zipper is a sturdy metal locking zipper, branded by a reputable company or trim maker, such as YKK,” says Janine Chilton-Faust, global vice-president of men’s design at Levi’s.

Every year, the Swedish denim brand Nudie Jeans repairs tens of thousands of pairs of jeans at its Nudie Jeans Repair Shops. So, we consulted Nudie Jeans denim designer Johan Lindstedt for some key tips on jean maintenance, particularly regarding washing (or, rather, not washing) them.

The “do-not-wash” rule

“I never wash my trousers, so I don’t know about detergent,” Lindstedt says. And that, in a nutshell, is the main thrust of his advice for taking care of jeans: don’t wash them. Not now. Not ever. Just wear one pair. A lot.

“All the indigo is on the surface of the fabric and washing destroys the fabric,” he says. “It takes about a year of constant wearing for the fades to become really beautiful. Washing them destroys the magic.”

The one-pair-at-a-time concept

Lindstedt recommends having just one pair of unwashed-denim jeans (denim that is stiff and dark blue, as opposed to washed, ie, pre-faded, varieties) and wearing the hell out of them.

“Choose one pair of dry-denim jeans, which you love and have a great fit, and wear them every day,” he says.

The quick fixes

There are a number of options if you feel you need to freshen your jeans up a bit. These are: leave them out in the open in damp weather for a few hours, put them in the freezer overnight or use a damp cloth to spot-clean any stains. The first two eliminate smells, the third saves you from having to wash the whole pair.

The last-resort clean

First, don’t wash them for at least six months. This is not only better for the planet, but vital for the look of your jeans. When you are ready to do the deed, there are two options.

The first is a mild, lukewarm soak, which gets rid of the grey-green surface grime that can accumulate. Simply fill up a bathtub with lukewarm water and a little detergent (no bleach or fabric softener) and let them soak for about 30 minutes.

The other option, which Lindstedt recommends after about a year or so of wear, or whenever you’ve achieved the pleasing abrasions and fadings you want, is to put them on a hot wash of 60 degrees (or more for the heavier Japanese selvedge denims). “This creates really high-contrast fades,” he says. “On Japanese selvedge, you get a kind of summer-clouds-against-blue-sky, California kind of vibe.”

Finally, stretch out the inseam before drying to prevent shrinkage, and let them dry naturally – definitely don’t use a tumble dryer.