In the United States, Ampex, using equipment obtained in Germany as a starting point, began commercial production of reel-to-reel tape recorders.

[14][15][16] Philips selected the two-spool cartridge as a winner and introduced the 2-track 2-direction mono version in Europe on 28 August 1963 at the Berlin Radio Show,[3][17][18][19][20][21][22] and in the United States (under the Norelco brand) in November 1964.

[27] The compact cassette format, however, was initially designed for dictation and portable use, and the audio quality of early players was not well-suited for music.

[29][30][31] Stereo tape decks and boom boxes became some of the most highly sought-after consumer products of both decades, as the ability of users to take their music with them anywhere with ease[17] led to its popularity around the globe.

[36] Critic Robert Palmer, writing in The New York Times in 1981, cited the proliferation of personal stereos as well as extra tracks not available on LP as reasons for the surge in popularity of cassettes.

Their small size, durability and ease of copying helped bring underground rock and punk music behind the Iron Curtain, creating a foothold for Western culture among the younger generations.

[46] Likewise, in Egypt cassettes empowered an unprecedented number of people to create culture, circulate information, and challenge ruling regimes before the internet became publicly accessible.

[50][51][52] Some pirate cassette producers created brands such as Cumbre y Cuatro that have in retrospect received praise for their contributions to popular music.

[52] Armed groups such as Manuel Rodríguez Patriotic Front (FPMR) and the Revolutionary Left Movement (MIR) made use of cassettes to spread their messages.

[58] For audiobooks, the final year that cassettes represented more than 50% of total market sales was 2002 when they were replaced by CDs as the dominant media.

[64] Although portable digital recorders are most common today, analog tape remains a desirable option for certain artists and consumers.

[67][68] Sony announced the end of cassette Walkman production on 22 October 2010,[69] a result of the emergence of MP3 players such as Apple's iPod.

[71] In 2010, Botswana-based Diamond Studios announced plans[72] for establishing a plant to mass-produce cassettes in a bid to combat piracy.

[79] In Japan and South Korea, the pop acts Seiko Matsuda,[80] SHINee,[81] and NCT 127 released their material on limited-run cassettes.

[93] Reasons cited for this include tradition, low cost,[29] the DIY ease of use,[94] and a nostalgic fondness for how the format's imperfections lend greater vibrancy to low-fi, experimental music, despite the lack of the "full-bodied richness" of vinyl.

c. 1970, 3M Company developed a cobalt volume-doping process combined with a double-coating technique to enhance overall tape output levels.

For this reason, some low-grade IEC Type I tapes have been marketed specifically as better suited for data storage than for sound recording.

The first CrO2 cassette was introduced in 1970 by Advent,[97] and later strongly backed by BASF, the inventor and longtime manufacturer of magnetic recording tape.

[98] Next, coatings using magnetite (Fe3O4) such as TDK's Audua were produced in an attempt to approach or exceed the sound quality of vinyl records.

"Type IV" tapes using pure metal particles (as opposed to oxide formulations) were introduced in 1979 by 3M under the trade name Metafine.

If the cassette is held with one of the labels facing the user and the tape opening at the bottom, the write-protect notch for the corresponding side is at the top-left.

[108][109] A common mechanical problem occurs when a defective player or resistance in the tape path causes insufficient tension on the take-up spool.

[116] A third company, Bang & Olufsen of Denmark, created the Dolby HX "head room extension" system for reliably reducing tape saturation effects at high frequencies while maintaining higher bias levels.

[3] In this capacity, some later-model cassette-based dictation machines could also run the tape at half speed (15⁄16 in/s) as playback quality was not critical.

As of 2009, one still found cassettes used for a variety of purposes, such as journalism, oral history, meeting and interview transcripts, audio books, and so on.

One artifact found on some commercially produced music cassettes was a sequence of test tones, called SDR (Super Dynamic Range, also called XDR, or eXtended Dynamic Range) soundburst tones, at the beginning and end of the tape, heard in order of low frequency to high.

However, many claimed that the medium was ideal for spreading new music and would increase sales, and strongly defended their right to copy at least their own records onto tape.

For a limited time in the early 1980s Island Records sold chromium dioxide "One Plus One"[125] Various legal cases arose surrounding the dubbing of cassettes.

[126] In a similar case, a shop owner who rented cassettes and sold blank tapes was not liable for copyright infringement even though it was clear that his customers likely were dubbing them at home.

A portable CD player would have its analog line-out connected to the adapter, which in turn fed the signal to the head of the cassette deck.