Along with the gradual displacement of the voice in favor of stronger, clearer melodies, counterpoint also typically became a decorative flourish, often used near the end of a work or for a single movement. In its stead, simple patterns, such as arpeggios and, in piano music, Alberti bass (an accompaniment with a repeated pattern typically in the left hand), were used to liven the movement of the piece without creating a confusing additional voice. The now-popular instrumental music was dominated by several well-defined forms: the sonata, the symphony, and the concerto, though none of these were specifically defined or taught at the time as they are now in music theory. All three derive from sonata form, which is both the overlying form of an entire work and the structure of a single movement. Sonata form matured during the Classical era to become the primary form of instrumental compositions throughout the 19th century.

The early Classical period was ushered in by the Mannheim School, which included such composers as Johann Stamitz, Franz Xaver Richter, Carl Stamitz, and Christian Cannabich. It exerted a profound influence on Joseph Haydn and, through him, on all subsequent European music. Wolfgang Amadeus Mozart was the central figure of the Classical period, and his phenomenal and varied output in all genres defines our perception of the period. Ludwig van Beethoven and Franz Schubert were transitional composers, leading into the Romantic period, with their expansion of existing genres, forms, and even functions of music.

Any attempt to arrive at a precise, all-encompassing definition of jazz is probably futile. Jazz has been, from its very beginnings at the turn of the 20th century, a constantly evolving, expanding, changing music, passing through several distinctive phases of development; a definition that might apply to one phase—for instance, to New Orleans style or swing—becomes inappropriate when applied to another segment of its history, say, to free jazz. Early attempts to define jazz as a music whose chief characteristic was improvisation, for example, turned out to be too restrictive and largely untrue, since composition, arrangement, and ensemble have also been essential components of jazz for most of its history. Similarly, syncopation and swing, often considered essential and unique to jazz, are in fact lacking in much authentic jazz, whether of the 1920s or of later decades. Again, the long-held notion that swing could not occur without syncopation was roundly disproved when trumpeters Louis Armstrong and Bunny Berigan (among others) frequently generated enormous swing while playing repeated, unsyncopated quarter notes.

Jazz, in fact, is not—and never has been—an entirely composed, predetermined music, nor is it an entirely extemporized one. For almost all of its history it has employed both creative approaches in varying degrees and endless permutations. And yet, despite these diverse terminological confusions, jazz seems to be instantly recognized and distinguished as something separate from all other forms of musical expression. To repeat Armstrong’s famous reply when asked what swing meant: “If you have to ask, you’ll never know.” To add to the confusion, there often have been seemingly unbridgeable perceptual differences between the producers of jazz (performers, composers, and arrangers) and its audiences. For example, with the arrival of free jazz and other latter-day avant-garde manifestations, many senior musicians maintained that music that didn’t swing was not jazz.

Most early classical composers (such as Aaron Copland, John Alden Carpenter—and even Igor Stravinsky, who became smitten with jazz) were drawn to its instrumental sounds and timbres, the unusual effects and inflections of jazz playing (brass mutes, glissandos, scoops, bends, and stringless ensembles), and its syncopations, completely ignoring, or at least underappreciating, the extemporized aspects of jazz. Indeed, the sounds that jazz musicians make on their instruments—the way they attack, inflect, release, embellish, and colour notes—characterize jazz playing to such an extent that if a classical piece were played by jazz musicians in their idiomatic phrasings, it would in all likelihood be called jazz.

But while people might quibble over specifics, rock music can generally be described as hard-edged music performed with electric guitars, bass, and drums and usually accompanied by lyrics sung by a vocalist. That sounds simple enough, but a closer look at the evolution of rock suggests how different styles and influences have shaped its development over the years.

Rock's Origins (1940s-1960s)

Rock’s origins can be traced to the late 1940s, when the popular styles of the day, country music and blues, morphed into a new sound aided by electric guitars and a steady drumbeat. Pioneering rock artists of the 1950s such as Chuck Berry leaned heavily on classic blues structures while demonstrating a flair as natural-born entertainers. In contrast to the safe pop music of the era, rock’s aggressive attack suggested a sexual freedom that was shocking during that conservative age.

By the early '60s, Berry’s followers, most notably the Rolling Stones, expanded rock’s scope by transitioning from singles artists into musicians capable of producing cohesive albums of songs. Embracing sex and youthful rebellion in their music, the Stones courted controversy but also elevated rock to new cultural heights.

Rock's Evolution (1970s)

As rock music became the dominant form of popular music, new bands built on their predecessors’ strengths while branching out into new sonic territory. Led Zeppelin gave rock a darker, heavier tone, becoming one of the '70s’ most popular bands and helping to kick-start a new genre known as hard rock or heavy metal.

Around the same time, Pink Floyd added psychedelic elements and complex arrangements, creating concept albums tied together by a single theme and meant to be absorbed in a single sitting. Albums such as "Dark Side of the Moon" were credited with spawning the progressive rock movement.

In the late '70s, in response to what they perceived as pretentious “hippie” bands such as Pink Floyd, groups including the Sex Pistols and the Clash simplified rock to its core ingredients: loud guitars, rude attitude, and enraged singing. Punk was born.

While all three movements enjoyed different degrees of mainstream acceptance, a fourth, less-recognized style was beginning to take shape. Spotlighting atonal noise and unconventional rock instruments such as drum machines, groups such as Pere Ubu became the pioneers of industrial rock, an abrasive subgenre that didn’t enjoy widespread popularity but inspired future rock bands.

Rock's Splintering (1980s)

As the '80s began, mainstream rock was losing commercial steam, its sound growing stale. In such a creatively stagnant environment, subgenres started to assert their dominance.

Inspired by punk’s outsider status and industrial’s eclectic instrumentation, keyboard-driven English bands such as Depeche Mode demonstrated a more introverted songwriting style, creating post-punk, also described as new wave.

Meanwhile, American groups including R.E.M. toyed with post-punk elements, balancing introspective lyrics with traditional rock-band arrangements. These bands were dubbed college rock because of their popularity on college radio stations.

By the end of the '80s, college rock had become such a lucrative alternative to mainstream rock that it received a new moniker: alternative rock. It was also called indie rock because the bands were often signed to small, independently owned labels.

Alternative rock cemented its cultural standing when the music magazine Billboard created a new chart in 1988 for alternative rock, which the publication classified as modern rock. For most music fans, terms such as modern rock, alternative, and indie are synonymous ways of describing this popular subgenre.

Rock's Re-Emergence (1990s-Present)

With the ascension of Nirvana's "Nevermind" in 1991, alternative rock became the dominant popular music. But while other bands soon sprang up as part of the so-called grunge movement (a merging of hard rock and punk), other groups, such as Soundgarden, straddled the worlds of alternative and mainstream rock music.

Exacerbated by the suicide of Nirvana's frontman Kurt Cobain, alternative music started to lose its luster by the middle of the decade, setting the stage for mainstream rock's reemergence.

One of the first bands to capitalize on mainstream rock’s comeback was Limp Bizkit, which melded hard rock and rap into a hybrid call rap-rock. Groups such as Staind and Puddle of Mudd followed in Limp Bizkit’s wake, though these bands focused on melodic hard rock rather than integrating rap into the mix.

Bands that had thrived during grunge’s heyday but didn’t easily fit into the alternative subgenre, such as the Red Hot Chili Peppers, continued to find audiences throughout the '90s. Additionally, groups that rose from the ashes of grunge, among them Foo Fighters, incorporated alternative music’s outsider energy to re-energize mainstream rock.

As rock music entered the 21st century, the most successful acts had the same spirit as their '60s predecessors, even if they sounded quite different. Linkin Park fuses hip-hop and metal, while 3 Doors Down emulates hard-rock traditions of the past while providing a contemporary spin. Undoubtedly, rock music will keep evolving, drawing from its rich history while continuing to keep its ear open for the next sonic reinvention.

For the past 50 years the most successful musical styles on the pop charts have continually changed and evolved. However, there are some consistent patterns in what is identified as pop music.

Pop music (a term that originally derives from an abbreviation of "popular") is usually understood to be commercially recorded music, often oriented towards a youth market, usually consisting of relatively short, simple songs utilizing technological innovations to produce new variations on existing themes.

Pop music has absorbed influences from most other forms of popular music, but as a genre is particularly associated with the rock and roll and later rock style

In the history of music, the term 'pop music' was first used in 1926. It was used to describe 'a piece of music having popular appeal'. Commercially recorded music, consisting of relatively short and simple love songs is known as 'pop music'.

It is associated with the 'rock and roll' style, often tailored for the youth market, which utilizes technological innovations to produce new variations on existing themes.

Pop music history states that the term 'pop music' originated in Britain in the mid-1950s which implied 'concerts appealing to a wide audience' or 'the non classical music, usually in the form of songs', performed by such artists as the Beatles, the Rolling Stones, Abba, etc.

If you go through 80's pop music history, you will notice that pop music, throughout its development has been influenced by most other genres of popular music.

Pop music picked up instrumentation from jazz and rock music, vocal harmonies from gospel music and soul music, formed from the sentimental ballads, tempo from dance music, support from electronic music and spoken passages from rap.

In 1950s television was introduced and visual presence of pop stars helped to gain more popularity. In 1960s, cheap portable transistor radios were introduced, which helped the teenagers to listen to music outside of the home.

By 1980s MTV favored the artists such as Michael Jackson, Prince and Madonna who had a strong visual appeal. Widespread use of the microphone, multi-track recording, and digital sampling were the other technological innovations which were responsible for the increasing popularity of pop music.

Though pop music had been dominated by the American music industry, most regions and countries have their own form of pop music. In 1980s video technique was introduced and pop albums became still more popular.

The American pop music history provides us information about the fact that the 1960s and '70s saw a number of important changes in American popular music, for instance, the development of a number of new styles, including heavy metal, punk, soul and hip hop.

1964
Apr 4, 1964 - During the week of April 4, 1964, two months after their arrival in the US, the Beatles set a record that is likely never to be broken when they occupied all five of the top positions on Billboard's Top Pop Singles chart, with "Can't Buy Me Love?

1967
Jun 1, 1967 - June 1, 1967, is arguably the most important landmark in the history of pop music. The Rock'n'roll era commenced with 'Rock Around the Clock', with its opening up of the whole world of African tribal music and the unfettered emotion that went with it.

1970
Mar 27, 1970 - She was born Mariah Angela Carey on Long Island, New York, on March 27, 1970. Her mother, an Irish-American opera singer and vocal coach, Patricia Hickey, named her after the song "They Call the Wind Mariah" from the Broadway musical Paint Your Wagon.

1981
Aug 1, 1981 - MTV went on the air on August 1, 1981, and produced its first Video Music Awards just three years later. That makes for almost three decades of marrying the most popular pop music with televised spectacle.

1984
Nov 30, 1984 - Gergana was born in 30th of November, 1984 in Dimitrovgrad. In fact Dimitrovgrad is the house of Payner Music, and the place where producer made its first steps. This helped for the singer to realize her dream and to sing pop-folk music.

1995
Aug 1995 - single "You Are Not Alone", released in August 1995, is the second single from Michael Jackson's album History. The song was the singer's final Number 1 single of his career. The song was a significant success.

1998
Jul 15, 1998 - Both quoted in N. Strauss, "Japan's Pop Music Scene: Tomorrow, the World?"

2006
Aug 14, 2006 - It was said that on the 14 August 2006 Ryan would release "Je t'adore" in the UK for which exclusive mixes by Credheadz were commissioned, but the release was shelved, close to the release date. It did however enjoy heavy rotation on the UK's music channels ...

2007
Jun 7, 2007 - The Italian singer Adamo mainly made his career in Belgium. 2010
Mar 9, 2010 - "Pop", The Oxford Dictionary of Music. Accessed online on March 9, 2010.