Now on Netflix, the movie tracks the life of the American conductor and composer and his wife, the actress Felicia Montealegre, played by Carey Mulligan.Pop quiz: Who wrote the score for Bradley Cooper’s new Leonard Bernstein biopic, “Maestro”?Trick question: Bernstein. But you might not realize it, or learn of some of his more lasting accomplishments (“West Side Story” erasure!), even after watching the entire film, which focuses on the personal life of the prodigiously talented musician.Which is to say, the film — which Cooper directed and starred in, and which is now streaming on Netflix — does not hand-hold. It assumes some basic familiarity with one of America’s most storied conductors and composers. Here’s a guide to help you get up to speed.His careerWhat is Bernstein best known for?One of the rare virtuosos to compose for musical theater, write classical music and conduct august bodies like the New York Philharmonic, Bernstein is probably best remembered as the composer of the 1957 musical “West Side Story.”The Manhattan-set tale of urban gang warfare in New York City, based on “Romeo & Juliet,” includes standards like “Tonight,” “I Feel Pretty” and the aching, wistful “Maria.” The classic show, a collaboration with Arthur Laurents, who wrote the book, and Stephen Sondheim, who penned the lyrics, won two Tony Awards in its original incarnation.In his day, Bernstein was known first and foremost as an animated, passionate conductor. After his spectacular fill-in debut at the Philharmonic at age 25 in 1943 — on just a few hours’ notice, because the scheduled guest conductor fell ill — Bernstein would be affiliated with the orchestra for four decades and conduct symphonies around the world.He also wrote classical music, including three symphonies, “Jeremiah,” “The Age of Anxiety” and “Kaddish,” and made the classical realm accessible to ordinary Americans through his Young People’s Concerts. Those televised lectures, which ran on CBS for 14 years, covered a broad range of subjects including humor in music, and the composers Gustav Mahler and Igor Stravinsky.What is Tanglewood?Tanglewood, the summer home of the Boston Symphony Orchestra and its training academy in the Berkshire Hills in Massachusetts, is where Bernstein studied with Serge Koussevitzky, then the director of the ensemble. The two met in 1940, when Koussevitzky selected a 22-year-old Bernstein as one of three inaugural conducting fellows for the Berkshire Music Center, now known as the Tanglewood Music Center.Bernstein went on to teach and perform there nearly every summer for 50 years, becoming the head of orchestral conducting at Tanglewood after Koussevitzky died in 1951. In 1990, Bernstein led the final performance of his life there — a gripping account of Beethoven’s Seventh Symphony.How much of the film’s score is Bernstein’s music?That cue you hear when Bernstein finds out he’ll be making his conducting debut at the New York Philharmonic? That’s from “On the Waterfront,” the 1954 Marlon Brando drama for which Bernstein wrote the music. That spiky, horn-filled composition that signals tension when Bernstein and a male lover arrive at the family’s Connecticut home? That’s the prologue from “West Side Story.”In fact, most of the music you hear was written by Bernstein. (Also see if you can spot classical excerpts from his ballets “Facsimile” and “Fancy Free,” his opera “A Quiet Place,” and parts of his second and third symphonies.)His personal lifeWas Bernstein gay or bisexual?Though he was married to his wife, the actress Felicia Montealegre (Carey Mulligan), for 26 years, he had numerous relationships — with both men and women — before and during their marriage, and after her death in 1978.The film focuses on two of them — his dalliance with the clarinetist David Oppenheim (Matt Bomer), whose bottom Bernstein slaps at the beginning of the film, and the musician Tom Cothran (Gideon Glick), whom he steals kisses with at a party and brings to his Connecticut home.What was society’s attitude toward gay people at the time?Anti-gay prejudice was rampant in America in the 1940s and 1950s, and the Lavender Scare — a fear that homosexual people had infiltrated the federal government and were a threat to national security — led to the dismissal of gay and lesbian employees, and those assumed to be, en masse. Gay, lesbian and transgender people — particularly public figures — faced intense pressure to conceal their identities, and Bernstein worried that the public revelation of his sexual orientation would hurt his conducting prospects.Did Montealegre know Bernstein was gay or bisexual when she married him?Yes, according to a letter she wrote to him the year after they were married, which the couple’s children discovered after her death. “You are a homosexual and may never change,” she wrote, adding later, “I am willing to accept you as you are, without being a martyr.” She went on to tell him, “Let’s try and see what happens if you are free to do as you like, but without guilt and confession.”Was Bernstein open about his affairs with men?At first, he was discreet, heeding Montealegre’s request to not embarrass her publicly. But, as “Maestro” shows, he became “sloppy” later or, rather, decided that he no longer wanted to hide what he viewed as a fundamental part of himself amid society’s changing attitudes.In 1976, he briefly left Montealegre to live openly with his boyfriend, Cothran, though he returned to her a year later when she learned she had lung cancer and cared for her until she died at age 56.What did Bernstein say about his sexuality?Nothing, at least, publicly. But privately, he suffered through years of therapy, apparently in the hope that he could be “cured” of his attraction to men. That desire lasted a lifetime: “I have been engaged in an imaginary life with Felicia,” he wrote in a letter to his sister, Shirley, from Israel in 1950, “having her by my side on the beach as a shockingly beautiful Yemenite boy passes.”Did Bernstein love his wife?Bernstein was “a gay man who got married,” his “West Side Story” collaborator Arthur Laurents once said in response to the assumption that Bernstein, who had three children with Montealegre, was bisexual. “He wasn’t conflicted about his sexual orientation at all. He was just gay.”But what is clear, from their children’s memories and from Bernstein’s own letters, is that he and Montealegre had an abiding affection for one another, and that their relationship was built on tenderness and mutual respect.“Bernstein absolutely loved her — there was no question about that,” Paul R. Laird, the author of “Leonard Bernstein,” a 2018 biography, recently told Time magazine. “It was as sincere a marriage as you’re going to get between a male homosexual and a woman at a time when a lot of male homosexuals married women.”Bernstein’s oldest daughter, Jamie, has spoken about her parents’ friendship. “They were really great friends, and probably that counts for the most in the long run, that they could still make each other laugh,” she said in a 1997 PBS interview.How did Bernstein die?He had received an emphysema diagnosis in his mid-20s — he would struggle with addiction to cigarettes and alcohol for most of his life — and died on Oct. 14, 1990, at 72, of a heart attack caused by lung failure.He was often depressed in his later years, intimidated that he would be best remembered as a conductor, resigned to the fact that he could never live up to the success of “West Side Story,” and guilty about his wife’s death from cancer, which he held himself responsible for. More