Compact cassette in the context of "List of magnetic tape cartridges and cassettes"

Sheet music is a handwritten or printed form of musical notation that uses musical symbols to indicate the pitches, rhythms, or chords of a song or instrumental musical piece. Like its analogs – printed books or pamphlets in English, Arabic, or other languages – the medium of sheet music typically is paper (or, in earlier centuries, papyrus or parchment). However, access to musical notation since the 1980s has included the presentation of scores on computer screens and the development of scorewriter computer programs that can notate a song or piece electronically, and, in some cases, "play back" the notated music using a synthesizer or virtual instruments.

The use of the term sheet is intended to differentiate written or printed forms of music from sound recordings (on vinyl record, cassette, CD), radio or TV broadcasts or recorded live performances, which may capture film or video footage of the performance as well as the audio component. In everyday use, sheet music (or simply music) can refer to the print publication of commercial sheet music in conjunction with the release of a new film, TV show, record album, or other unique or popular event which involves music. The first printed sheet music made with a printing press was made in 1473.

A disc jockey, more commonly abbreviated as DJ, is a person who plays recorded music for an audience. Types of DJs include radio DJs (who host programs on music radio stations), club DJs (who work at nightclubs or music festivals), mobile DJs (who are hired to work at public and private events such as weddings, parties, or festivals), and turntablists (who use record players, usually turntables, to manipulate sounds on phonograph records). Originally, the "disc" in "disc jockey" referred to shellac and later vinyl records, but nowadays DJ is used as an all-encompassing term to also describe persons who mix music from other recording media such as cassettes, CDs or digital audio files on a CDJ, controller, or even a laptop. DJs may adopt the title "DJ" in front of their real names, adopted pseudonyms, or stage names.

DJs commonly use audio equipment that can play at least two sources of recorded music simultaneously. This enables them to blend tracks together to create transitions between recordings and develop unique mixes of songs. This can involve aligning the beats of the music sources so their rhythms and tempos do not clash when played together and enable a smooth transition from one song to another. DJs often use specialized DJ mixers, small audio mixers with crossfader and cue functions to blend or transition from one song to another. Mixers are also used to pre-listen to sources of recorded music in headphones and adjust upcoming tracks to mix with currently playing music. DJ software can be used with a DJ controller device to mix audio files on a computer instead of a console mixer. DJs may also use a microphone to speak to the audience; effects units such as reverb to create sound effects and electronic musical instruments such as drum machines and synthesizers.

A tape head is a type of transducer used in tape recorders to convert electrical signals to magnetic fluctuations and vice versa. They can also be used to read credit/debit/gift cards because the strip of magnetic tape on the back of a credit card stores data the same way that other magnetic tapes do. Cassette tapes, reel-to-reel tapes, 8-track tapes, VHS tapes, and even floppy disks and early hard disk drives all use the same principle of physics to store and read back information. The medium is magnetized in a pattern. It then moves at a constant speed over an electromagnet. Since the moving tape is carrying a changing magnetic field with it, it induces a varying voltage across the head. That voltage can then be amplified and connected to speakers in the case of audio, or measured and sorted into ones and zeroes in the case of digital data.

Reel-to-reel audio tape recording, also called open-reel recording, is magnetic tape audio recording in which the recording tape is spooled between reels. To prepare for use, the supply reel (or feed reel) containing the tape is placed on a spindle or hub. The end of the tape is manually pulled from the reel, threaded through mechanical guides and over a tape head assembly, and attached by friction to the hub of the second, initially empty takeup reel. Reel-to-reel systems use tape that is 1⁄4, 1⁄2, 1, or 2 inches (6.35, 12.70, 25.40, or 50.80 mm) wide, which normally moves at 3+3⁄4, 7+1⁄2, 15 or 30 inches per second (9.525, 19.05, 38.10 or 76.20 cm/s).

Reel-to-reel preceded the development of the compact cassette with its tape 0.15 inches (3.8 mm) wide moving at 1+7⁄8 inches per second (4.8 cm/s). By writing the same audio signal across more tape, reel-to-reel systems give much greater fidelity at the cost of much larger tapes. In spite of the relative inconvenience and generally more expensive media, reel-to-reel systems developed in the early 1940s remained popular in audiophile settings into the 1980s and have re-established a specialist niche in the 21st century.

The 8-track tape (formally Stereo 8; commonly called eight-track cartridge, eight-track tape, and eight-track) is a magnetic-tape sound-recording technology that was popular from the mid-1960s until the early 1980s, when the compact cassette, which antedated the 8-track system, surpassed it in popularity for recorded music.

The format was commonly used in cars and was most popular in the United States and Canada, and to a lesser extent, in the United Kingdom, Ireland, and Japan. One advantage of the 8-track tape cartridge was that it could play continuously in an endless loop, and did not have to be ejected, turned around, and reinserted to play the entire tape. After about 80 minutes of playing time, the tape would start again at the beginning. Because of the loop, no rewind is needed. The only options the user has are play, fast forward, record, and program (track) change.

A DJ mixer is a type of audio mixing console used by disc jockeys (DJs) to control and manipulate multiple audio signals. Some DJs use the mixer to make seamless transitions from one song to another when they are playing records at a dance club. Hip hop DJs and turntablists use the DJ mixer to play record players like a musical instrument and create new sounds. DJs in the disco, house music, electronic dance music and other dance-oriented genres use the mixer to make smooth transitions between different sound recordings as they are playing. The sources are typically record turntables, compact cassettes, CDJs, or DJ software on a laptop. DJ mixers allow the DJ to use headphones to preview the next song before playing it to the audience. Most low- to mid-priced DJ mixers can only accommodate two turntables or CD players, but some mixers (such as the ones used in larger nightclubs) can accommodate up to six turntables or CD players. DJs and turntablists in hip hop music and nu metal use DJ mixers to create beats, loops and so-called scratching sound effects.