Blankets spread on the lawn; warm brie and warm wine and a flickering candle dripping wax on the grass; the sound of crickets chirping gentlyin the background; an illuminated stage in the distance with the sound of the “1812 Overture” mixing with the night air and the hum of a mosquito hovering over your thigh. There’s something archetypal about the summer concert experience: a time when great music is there for everyone and people allow themselves, rather than listening in solemn churchlike silence in a concert hall, to kick back, refill their glasses and enjoy it.

Festivals form an occasion for performers to travel from around the country, and the world, to join together in performances of particular kinds of music. In June, the churches of Washington are colonized by ensembles taking part in the Washington Early Music Festival, which under this year’s heading of “Vices and Virtues: Passionate Music of Early Europe” will unite such local groups as the Suspicious Cheese Lords, Harmonious Blacksmith and the Baltimore Consort with national and international ones such as Le Tendre Amour, based in Barcelona. Choral music from around the world is the focus of “Serenade!” which for four days at the end of June and start of July will present international choruses in concerts, most of them free, including a seven-chorus marathon giving a cross-section of the whole event at Strathmore.

Festivals are a time when people who want to make music can advance their training and get performing experience under their belt. Young professionals hone their trade at the Wolf Trap Opera — “Don Giovanni” and “The Rake’s Progress” will be this summer’s offerings — or the National Orchestral Institute. Adult amateurs pay to attend a kind of orchestral summer-cum-boot camp and play under Marin Alsop at the second iteration of the Baltimore Symphony Orchestra’s program called simply The Academy, or join in free summer sing-alongs every Tuesday in June of major works in the choral repertoire with leading Washington-area choral directors.

Festivals are a chance for artists and audiences to get up close and personal to stars and leaders who let their hair down: Sherrill Milnes at the Vocal Arts and Music Festival at Virginia Tech, Alsop at the Academy, Lorin Maazel at Castleton, Leon Fleisher at the Washington International Piano Festival and the Kapell Competition. For even competitions become festivals; at the Kapell, the competition rounds alternate with master classes and performances by some major soloists (Jeremy Denk, Richard Egarr, and others.)

Summer festivals make people who normally don’t go to classical concerts think it might be fun to attend one, whether that means sitting by the river at St. Mary’s College of Maryland or making a weekend of it at the Garth Newel Music Center in Hot Springs, Va., where you can stay overnight in the manor house and be served dinner along with the performers after the show.

They demystify opera, encouraging some of the original populist spirit of the genre, be it through the Ash Lawn Opera in Charlottesville, juxtaposing “The Magic Flute” and “The Music Man,” or the mix of students and young artists in the joint Bel Cantanti-Catholic University Summer Opera Festival, offering “Carmen” and “Le nozze di Figaro” right here in Washington.

Indeed, they restore the enjoyment to classical music. There are certainly festivals that offer major orchestral programs — Tanglewood with the Boston Symphony Orchestra, Ravinia with the Chicago Symphony Orchestra — but Washington doesn’t happen to have one. Here, the line between pops and classical is blurred with the heat, so that at Wolf Trap, on the stage at the bottom of the natural amphitheater’s sloping hillside, the National Symphony Orchestra plays Beethoven’s Ninth one night and music from the video game “The Legend of Zelda” another, and then moves on to the Mall for its traditional concerts on Memorial Day, the Fourth of July and Labor Day. At National Harbor, meanwhile, the Chesapeake Orchestra is inaugurating an all-pops series on Saturday nights. So you can sit by the Potomac, watch the sunset and enjoy a little “Rhapsody in Blue” or Mozart or Dvorak’s “New World” symphony, free of charge. That’s what summer music is all about.