“I’m writing to ask for advice,” the e-mail began. “I want to know more about contemporary music. Where should I start?”

I get letters like this every few months, and I am often puzzled about how to answer. Gone are the days when there was a fixed canon of “good” composers (or, worse, “approved” ones), and a critic told you what you were supposed to like. Today, musical taste has blown wide open. If you love music, chances are that you like lots of different things: Ornette Coleman and Bruce Springsteen and Dmitri Shostakovich and Sufjan Stevens. If you’re a longtime orchestra subscriber, you may be passionate about Brahms but leery of the unfamiliar names and sounds that occasionally emerge onto concert programs. And chances are, whatever you like, you are equally passionate about what you don’t like — even more passionate, in fact, to judge from some of the rest of my mail.

So here, O fictive reader, are answers to some of the questions that, over the years, I’ve heard you ask. These answers are the equivalent of a one-day tour of a major metropolis, pointing out a few highlights to give you a general sense of the landscape of living composers, hoping that you’ll return to visit, in depth, whatever grabs your interest. This is not a “best of” guide, but rather an aide to orientation: Whatever your individual taste, these are pieces worth exploring.

1.Why should I care about minimalism?

Minimalism is a frustratingly incorrect term for a compositional approach that developed in the second half of the 20th century and that, in hindsight, turns out to be the most important contribution the United States has made to the field of composition.

(Susana Sanchez-Young/The Washington Post; iStockPhoto.com)

“Minimalism” is a flawed term because most of the composers associated with it — notably Steve Reich and Philip Glass — reject it. It’s also a term that inspires fear and loathing in the hearts of some listeners who think it describes works that simply do the same thing over and over and over and over again — like passages of Glass's seminal and divisive 1976 opera “Einstein on the Beach.” “It’s not music,” say detractors.

Ah, but it is. Even the earliest seminal works of so-called minimalism share a lyric freshness. They do indeed take a step away from the conventional narrative of traditional classical music forms. Rather than taking a theme and develop it, they put musical elements together and let them shift into different, ever-changing combinations, like images in a kaleidoscope. The classic example is Terry Riley’s “In C” from 1964, consisting of 53 numbered phrases that are played by any number of musicians, lasting anywhere from 10 minutes to a couple of hours, creating a dreamy, beguiling, mutable colorscape in the process. Equally iconic is Reich’s “Music for 18 Musicians,” which references influences all the way back to medieval chant in the way it revolves around the same 11 chords, played at different speeds, within the compass of individual human breaths.

And the real hallmark of so-called minimalist music is not its repetition but this way of approaching musical form. (Anton Bruckner, the 19th-century symphonic composer, has been called a proto-minimalist for the way he juxtaposes great blocks of sound.) As minimalist ideas have evolved, the genre’s sounds have become ever richer. Louis Andriessen, the maverick Dutch composer, has jokingly called himself a “maximalist” (check out his huge, powerful opera-oratorio “De Materie” to hear the way he creates powerful music out of layers of sound). John Adams, who used to be seen as a young minimalist, now writes scores with veritably Wagnerian overtones for full orchestra and/or opera. (My favorite introduction to Adams is “Harmonium,” a big, shining, early piece for chorus and orchestra that radiantly sets texts by John Donne and Emily Dickinson, ending in a whirl of taut, bright sound.)

Bottom line: “Minimalism” isn’t the threat to classical music’s bastion that some people have perceived it to be. Instead, it has provided a new strain of energy and ideas that have helped revivify the field and continues to influence new works, even by composers who aren’t labeled “minimalist” at all.

2. I like traditional orchestral music. Why can’t they just go on writing that?

They can, and they do. The conventional wisdom is that contemporary music in the 20th century was taken over by serialism, a compositional technique that involves creating music according to series of values other than melody and harmony. (The most notorious serialist technique is 12-tone music, which creates a musical phrase by combining all 12 notes of the chromatic scale in a fixed order, and then uses that phrase as the basis of a musical work.) The resulting works are sometimes fascinating, but seem difficult and unappealing to some lay audiences; and (still following the conventional wisdom) a generation of composers shied away from serialist strictures. Minimalism was one reaction; neo-romanticism — a return to the melodic, tonal, timbral values of romantic music — was another. This story is a little too pat — for one thing, neo-romanticism has been a force in American music throughout the 20th century (see Samuel Barber) — but it’s certainly true that David Del Tredici, for one, got a lot of attention back in the 1980s when he turned from serialist orthodoxy and began writing big, lush scores for full orchestra (including “Final Alice”).

Like minimalism, neo-romanticism is a facile and not entirely accurate label. It’s often applied, for instance, to John Corigliano, who writes well for orchestra and with an acute sense of the past — his 1991 opera “The Ghosts of Versailles” is one of the best syntheses of the grand opera tradition and contemporary music that anyone’s managed to come up with — but whose sensibility, sound, and sophistication are firmly rooted in the present. The neo-romantic sensibility, however, is kept most vividly alive in contemporary American opera, which tends to pursue a kind of Broadway-like accessibility in a tonal musical language, from William Bolcom’s “A View from the Bridge” to Jake Heggie’s recent “Moby-Dick.”

But neo-romanticism isn’t the only path composers use to access traditional forms with a fresh eye. Some of today’s most successful orchestral composers are writing symphonies and concertos — like Jennifer Higdon, whose Percussion Concerto won a Grammy in 2010, and whose Violin Concerto was recently recorded to great acclaim by Hilary Hahn (though not everyone shared my affection for her Piano Concerto at its NSO premiere). Higdon writes athletic, energetic music that’s smart and solid and wins over audiences, bright and forward-propelled as a Tour de France rider.

Another acclaimed recent concerto was written by the Finnish composer-conductor Esa-Pekka Salonen, best known in this country for the years he spent as music director of the Los Angeles Philharmonic (1992-2009). His Piano Concerto sounds as if it had been written to reassure those who were worried that, when he stepped down from the post to devote himself entirely to composing, he was going to float off into the world of the avant-garde. Without losing the quirky touch of his earlier compositions, this concerto is rife with references to its virtuosic predecessors in the canon: You can hear hints of Prokofiev, Rachmaninov, Ravel in what amounts to one long finger-busting, hyperactive, crowd-pleasing outburst. When a composer spends years conducting week in and week out, he sure ends up knowing how to write for an orchestra.

3.What about the younger generation? And what is this “alt-classical” stuff you keep praising?

“Younger generations” are notoriously slippery things in this field: Anybody under 50 still counts as “young.” “Young,” indeed, becomes more about an attitude than chronological age: Writing music that incorporates electric guitar and acoustic violin is now a hallmark of the 50-something set, from Steven Mackey, the guitarist turned Princeton teacher, to the Bang on a Can All-Stars, the performing arm of the eponymous composers’ collaborative formed by David Lang, Michael Gordon and Julia Wolf. The idea that good music can bring together a range of traditions, from rock to West African drumming to Javanese gamelan, is today a given for most younger composers, and emerges in surprising ways (like Lang’s “Little Match Girl Passion,” a translucent piece for small chorus that won him the Pulitzer Prize).

Another current trend that’s been on the rise over the last five decades is the return to the age of the composer-performer. Those who write music and want it performed go out and play it themselves — like Derek Bermel, a clarinet player whose Clarinet Concerto “Voices” mingles elements of a wide range of musics in ways both thoughtful and fun — or form their own bands, like Missy Mazzoli, whose group Victoire played the Library of Congress earlier this summer with music from their debut album.

“Alt-classical” is a term coined to describe the indie-rock sensibility of a lot of these genre-defying efforts, which are becoming ever more prevalent on every level of the musical establishment. Riccardo Muti and the Chicago Symphony Orchestra took the notable step last year of naming, as co-composers in residence, Mason Bates, who has an active career as a DJ as well as writing works for places like the San Francisco Symphony, and Anna Clyne, another 30-something who incorporates sampling and amplification in her music.

That’s not to say that all young composers are wedded exclusively to rock-inspired sounds: simply that genre boundaries no longer function as limits. Nico Muhly, who turns 30 this summer, is one of the most successful composers around, with two operas opening this calendar year (one, “Two Boys,” will appear at the Metropolitan Opera in 2013-14); a musical omnivore, he is inspired by everything from the English choral tradition to Icelandic pop to Philip Glass. And Jefferson Friedman, who has played with several rock groups, has written some of the best contemporary string quartets I know.

4. Tell me the names of some significant contemporary composers or pieces you think everyone should know.

Here are a few iconic works by a few major living composers whom I haven’t yet mentioned:

George Crumb, “Black Angels,” a searing expressionistic string quartet written during the Vietnam War by a distinctive musical maverick.

Meredith Monk, “Songs of Ascension,” the latest recording by one of our greatest innovators, rich treasure from the seam of expanded vocal techniques and artless sound juxtapositions that she’s been mining tirelessly for decades.

Frederic Rzewski, “The People United Will Never Be Defeated,” an hour-long, impassioned, political, eclectic set of variations (including shouting at the piano) on a Chilean protest song.

Elliott Carter, First String Quartet, a breakout work from 1951 that still sounds as radical and new as it did when it was written, by the grand old man of the 20th-century American establishment, who’s still going strong at 102.

Pierre Boulez, “Pli selon pli,” one of the longest and in many ways most beautiful pieces, a lyrical exegesis on poems by the French symbolist poet Stephane Mallarme in which a high soprano soars over and around the instruments of the orchestra, written by a former lion of European serialism who has mellowed considerably in his later years.

Via Spotify, listen to the music from this story on our contemporary classical playlist. Read more about classical music on Anne Midgette’s blog, The Classical Beat.