Publications produced without the official approval of a dominant group
The terms underground press or clandestine press refer to periodicals and publications that are produced without official approval, illegally or against the wishes of a dominant (governmental, religious, or institutional) group. 
In specific recent (post-World War II) Asian, American and Western European context, the term "underground press" has most frequently been employed to refer to the independently published and distributed underground papers associated with the counterculture of the late 1960s and early 1970s in India and Bangladesh in Asia, in the United States and Canada in North America, and the United Kingdom and other western nations. It can also refer to the newspapers produced independently in repressive regimes. In German occupied Europe, for example, a thriving underground press operated, usually in association with the Resistance. Other notable examples include the "samizdat" and "bibuła", which operated in the Soviet Union and Poland respectively, during the Cold War.
Origins.
In Western Europe, a century after the invention of the printing press, a widespread underground press emerged in the mid-16th century with the clandestine circulation of Calvinist books and broadsides, many of them printed in Geneva, which were secretly smuggled into other nations where the carriers who distributed such literature might face imprisonment, torture or death. Both Protestant and Catholic nations fought the introduction of Calvinism, which with its emphasis on intractable evil made its appeal to alienated, outsider subcultures willing to violently rebel against both church and state. In 18th century France, a large illegal underground press of the Enlightenment emerged, circulating anti-Royalist, anti-clerical and pornographic works in a context where all published works were officially required to be licensed. Starting in the mid-19th century an underground press sprang up in many countries around the world for the purpose of circulating the publications of banned Marxist political parties; during the German Nazi occupation of Europe, clandestine presses sponsored and subsidized by the Allies were set up in many of the occupied nations, although it proved nearly impossible to build any sort of effective underground press movement within Germany itself.
The French resistance published a large and active underground press that printed over 2 million newspapers a month; the leading titles were "Combat", "Libération", "Défense de la France", and "Le Franc-Tireur". Each paper was the organ of a separate resistance network, and funds were provided from Allied headquarters in London and distributed to the different papers by resistance leader Jean Moulin. Allied prisoners of war (POWs) published an underground newspaper called POW WOW. In Eastern Europe, also since approximately 1940, underground publications were known by the name "samizdat".
The countercultural underground press movement of the 1960s borrowed the name from previous "underground presses" such as the Dutch underground press during the Nazi occupations of the 1940s. Those predecessors were truly "underground", meaning they were illegal, thus published and distributed covertly. While the countercultural "underground" papers frequently battled with governmental authorities, for the most part they were distributed openly through a network of street vendors, newsstands and head shops, and thus reached a wide audience.
The underground press in the 1960s and 1970s existed in most countries with high GDP per capita and freedom of the press; similar publications existed in some developing countries and as part of the "samizdat" movement in the communist states, notably Czechoslovakia. Published as weeklies, monthlies, or "occasionals", and usually associated with left-wing politics, they evolved on the one hand into today's alternative weeklies and on the other into zines.
In Australia.
The most prominent underground publication in Australia was a satirical magazine called "OZ" (1963 to 1969), which initially owed a debt to local university student newspapers such as Honi Soit (University of Sydney) and Tharunka (University of New South Wales), along with the UK magazine "Private Eye". The original edition appeared in Sydney on April Fools' Day, 1963 and continued sporadically until 1969. Editions published after February 1966 were edited by Richard Walsh, following the departure for the UK of his original co-editors Richard Neville and Martin Sharp, who went on to found a British edition ("London Oz") in January 1967. In Melbourne Phillip Frazer, founder and editor of pop music magazine "Go-Set" since January 1966, branched out into alternate, underground publications with "Revolution" in 1970, followed by "High Times" (1971 to 1972) and "The Digger" (1972 to 1975).
In the United Kingdom.
The underground press offered a platform to the socially impotent and mirrored the changing way of life in the UK underground.
In London, Barry Miles, John Hopkins, and others produced "International Times" from October 1966 which, following legal threats from "The Times" newspaper was renamed "IT".
Richard Neville arrived in London from Australia, where he had edited "Oz" (1963 to 1969). He launched a British version (1967 to 1973), which was A4 (as opposed to "IT"'s broadsheet format). Very quickly, the relaunched "Oz" shed its more austere satire magazine image and became a mouthpiece of the underground. It was the most colourful and visually adventurous of the alternative press (sometimes to the point of near-illegibility), with designers like Martin Sharp. 
Other publications followed, such as "Friends" (later "Frendz"), based in the Ladbroke Grove area of London; "Ink", which was more overtly political; and "Gandalf's Garden" which espoused the mystic path.
Legal challenges.
The flaunting of sexuality within the underground press provoked prosecution. "IT" was taken to court for publishing small ads for homosexuals; despite the 1967 legalisation of homosexuality between consenting adults in private, importuning remained subject to prosecution. Publication of the "Oz" "School Kids" issue brought charges against the three "Oz" editors, who were convicted and given jail sentences. This was the first time the Obscene Publications Act 1959 was combined with a moral conspiracy charge. The convictions were, however, overturned on appeal.
Harassment and intimidation.
Police harassment of the British underground, in general, became commonplace, to the point that in 1967 the police seemed to focus in particular on the apparent source of agitation: the underground press. The police campaign may have had an effect contrary to that which was presumably intended. If anything, according to one or two who were there at the time, it actually made the underground press stronger. "It focused attention, stiffened resolve, and tended to confirm that what we were doing was considered dangerous to the establishment", remembered Mick Farren. From April 1967, and for some while later, the police raided the offices of "International Times" to try, it was alleged, to force the paper out of business. In order to raise money for "IT" a benefit event was put together, "The 14 Hour Technicolor Dream" Alexandra Palace on 29 April 1967.
On one occasion – in the wake of yet another raid on "IT" – London's alternative press succeeded in pulling off what was billed as a 'reprisal attack' on the police. The paper "Black Dwarf" published a detailed floor-by-floor 'Guide to Scotland Yard', complete with diagrams, descriptions of locks on particular doors, and snippets of overheard conversation. The anonymous author, or 'blue dwarf', as he styled himself, claimed to have perused archive files, and even to have sampled one or two brands of scotch in the Commissioner's office. The London "Evening Standard" headlined the incident as "Raid on the Yard". A day or two later "The Daily Telegraph" announced that the prank had resulted in all security passes to the police headquarters having to be withdrawn and then re-issued.
Support from British pop culture.
By the end of the decade, community artists and bands such as Pink Floyd (before they "went commercial"), The Deviants, Pink Fairies, Hawkwind, Michael Moorcock and Steve Peregrin Took would arise in a symbiotic co-operation with the underground press. The underground press publicised these bands and this made it possible for them to tour and get record deals. The band members travelled around spreading the ethos and the demand for underground newspapers and magazines grew and flourished for a while.
Neville published an account of the counterculture called "Play Power", in which he described most of the world's underground publications. He also listed many of the regular key topics from those publications, including the Vietnam War, Black Power, politics, police brutality, hippies and the lifestyle revolution, drugs, popular music, new society, cinema, theatre, graphics, cartoons, etc.
Local papers.
Apart from publications such as "IT" and "Oz", both of which had a national circulation, the 1960s and 1970s saw the emergence of a whole range of local alternative newspapers, which were usually published monthly. These were largely made possible by the introduction in the 1950s of offset litho printing, which was much cheaper than traditional typesetting and use of the rotary letterpress. Such local papers included:
A 1980 review identified some 70 such publications around the United Kingdom but estimated that the true number could well have run into hundreds. Such papers were usually published anonymously, for fear of the UK's draconian libel laws. They followed a broad anarchist, libertarian, left-wing of the Labour Party, socialist approach but the philosophy of a paper was usually flexible as those responsible for its production came and went. Most papers were run on collective principles.
North America.
Legal definition of "underground".
In the United States, the term "underground" did not mean "illegal" as it did in many other countries. The First Amendment and various court decisions (e.g. "Near v. Minnesota") give very broad rights to anyone to publish a newspaper or other publication, and severely restrict government efforts to close down or censor a private publication. In fact, when censorship attempts are made by government agencies, they are either done in clandestine fashion (to keep it from being known the action is being taken by a government agency) or are usually ordered stopped by the courts when judicial action is taken in response to them.
A publication must, in general, be committing a crime (for example, reporters burglarizing someone's office to obtain information about a news item); violating the law in publishing a particular article or issue (printing obscene material, copyright infringement, libel, breaking a non-disclosure agreement); directly threatening national security; or causing or potentially causing an imminent emergency (the "clear and present danger" standard) to be ordered stopped or otherwise suppressed, and then usually only the particular offending article or articles in question will be banned, while the newspaper itself is allowed to continue operating and can continue publishing other articles.
In the U.S. the term "underground newspaper" generally refers to an independent (and typically smaller) newspaper focusing on unpopular themes or counterculture issues. Typically, these tend to be politically to the left or far left. More narrowly, in the U.S. the term "underground newspaper" most often refers to publications of the period 1965–1973, when a sort of boom or craze for local tabloid underground newspapers swept the country in the wake of court decisions making prosecution for obscenity far more difficult. These publications became the voice of the rising New Left and the hippie/psychedelic/rock and roll counterculture of the 1960s in America, and a focal point of opposition to the Vietnam War and the draft.
Origins.
The North American countercultural press of the 1960s drew inspiration from predecessors that had begun in the 1950s, such as the "Village Voice" and Paul Krassner's satirical paper "The Realist." Arguably, the first underground newspaper of the 1960s was the "Los Angeles Free Press", founded in 1964 and first published under that name in 1965. 
1965–1973 boom period.
According to Louis Menand, writing in "The New Yorker", the underground press movement in the United States was "one of the most spontaneous and aggressive growths in publishing history." During the peak years of the phenomenon, there were generally about 100 papers currently publishing at any given time. But the underground press phenomenon proved short-lived.
An Underground Press Syndicate (UPS) roster published in November 1966 listed 14 underground papers, 11 of them in the United States, two in England, and one in Canada. Within a few years the number had mushroomed. A 1971 roster, published in Abbie Hoffman's "Steal This Book", listed 271 UPS-affiliated papers; 11 were in Canada, 23 in Europe, and the remainder in the United States. The underground press' combined readership eventually reached into the millions.
The early papers varied greatly in visual style, content, and even in basic concept — and emerged from very different kinds of communities. Many were decidedly rough-hewn, learning journalistic and production skills on the run. Some were militantly political while others featured highly spiritual content and were graphically sophisticated and adventuresome.
By