Hip hop's "golden age" (or "golden era") is a name given to a period in mainstream hip hop, usually cited as being a period varying in time frames during the 1980s and 1990s said to be characterized by its diversity, quality, innovation and influence. There were strong themes of Afrocentricity and political militancy, while the music was experimental and the sampling eclectic. The artists most often associated with the phrase are RunD.M.C.. (though they started around the ol skool era), Public Enemy, Beastie Boys (like Run-DMC they started around the ol skool era), Boogie Down Productions, Eric B. & Rakim, Big Daddy Kane, De La Soul, EPMD, A Tribe Called Quest, and the Jungle Brothers. Releases by these acts co-existed in this period with, and were as commercially viable as, those of early gangsta rap artists such as N.W.A., the sex raps of 2 Live Crew, and party-oriented music by acts such as Kid 'n Play and DJ Jazzy Jeff & The Fresh Prince.
The golden age is noted for its innovation a time when it seemed that every new single reinvented the genre according to Rolling Stone. Referring to hip-hop in its golden age, Spins editor-in-chief Sia Michel says, there were so many important, groundbreaking albums coming out right about that time, and MTVs Sway Calloway adds: "The thing that made that era so great is that nothing was contrived. Everything was still being discovered and everything was still innovative and new. Writer William Jelani Cobb says "what made the era they inaugurated worthy of the term golden was the sheer number of stylistic innovations that came into existence... in these golden years, a critical mass of mic prodigies were literally creating themselves and their art form at the same time".
It also provided some of the greatest advances in rapping technique - Kool G Rap, referring to the golden age in the book How to Rap says, that era bred rappers like a Big Daddy Kane, a KRS-One, a Rakim, a Chuck D. . . their rapping capability and ability - these dudes were phenomenal.
Many of hip-hop's biggest artists were also at their creative peak. The golden age, witnessed the best recordings from some of the biggest rappers in the genre's history. Golden age rap is characterized by skeletal beats, samples cribbed from hard rock, P-funk, contemporary jazz, R&B or soul tracks, and tough diss raps... rhymers like PE's Chuck D, Big Daddy Kane, KRS-One, Rakim, and LL Cool J basically invented the complex wordplay and lyrical kung-fu of later hip-hop.
There was also often an emphasis on black nationalism during the golden age of hip hop, from 1987 to 1993, Afrocentric and black nationalist rap were prominent, and when the form most capably fused the militancy of its Black Panther and Watts Prophets forebears with the wide-open cultural experimentalism of De La Soul and others.
Stylistic variety was also prominent rappers had an individual sound that was dictated by their region and their communities, not by a marketing strategist and essentially making the golden age Hip-Hop's era of eclecticism. It's also have been noted that albums from the Golden/Silver age also tended to have themes, and a consistent sound.
However, the specific time period that the golden age covers varies among different sources. The New York Times defines hip-hop's golden age as the "late 1980's and early 90's. In the book Contemporary Youth Culture, the "golden age era" is described as being "from 19871999", coming after "the old school era: from 1979 to 1985". Some refer to the period of 19931995, or 1993 to 1999 as "a second Golden Age" (or a Silver Age) that saw influential, high quality albums using elements of past classicism E-mu SP-1200 drum sounds, turntable scratches, references to old school hip hop hits, and "tongue-twisting triplet verbalisms" while making clear that new directions were being taken. People list as examples the Wu-Tang Clan's Enter the Wu-Tang (36 Chambers), Nas' Illmatic, De La Soul's 1993 release Buhloone Mindstate, Snoop Dogg's Doggystyle, A Tribe Called Quest's third album Midnight Marauders, Music/Mobb Deep's The Infamous (95), Bone Thugs-n-Harmony's first two albums (Creepin On Ah Come Up 94, and E.1999 Eternal 95), The Notorious B.I.G.'s Ready to Die (94), and OutKast's debut Southernplayalisticadillacmuzik (94), and their later 90's albums. So at the very least it's late '80s, to about early to mid/late '90s.
Either way The '90s as a whole were a turning point for rap music. The decade introduced a large array of sub-genres that showed that rap could be more than just block party music, and that it could also have strong messages and themes (much to the chagrin of fans who were used to it just being "fun"). It also saw the growth in rap's popularity outside of New York City, or New Jersey (Like New Orleans, Atlanta, Los Angeles, Memphis, Houston, Cleveland, Detroit, and Flint Michigan, Miami, Chicago). And the rise of prosperous Hip-Hop record labels, resulting in what is arguably the climax of the Golden Age era. Incidentally, the late 80s/early 90s are also the period where rap started to grow outside of the United States, each country starting to develop its own specificities in its approach of the genre. France notably had its own golden age in the 90's and early 2000's, an entire French generation growing up with MC Solaar, IAM, NTM, Ärsenik or Oxmo Puccino, to name a few.
For a nice look at this era check out Big Fun in the Big Town, a 1986 Dutch documentary about hiphop that has since then become a Cult Classic. This entire movie is a nostalgic trip to the time of old school hiphop, with many pioneers being interviewed, including RunD.M.C., Doug E Fresh, Grandmaster Flash and the Furious Five, LL Cool J, The Last Poets and Schoolly D. At the time of recording the genre was still mostly underground, with only a few acts starting to making it big. Many people, and not only in the USA, weren't sure whether the genre was just a passing fad or if it had staying power? By the time the episode got on the air "Walk This Way" by Run-D.M.C. was a huge hit and Hip-Hop finally caught on worldwide, even with people who weren't black. In that regard the docu is a nice Unintentional Period Piece.