poster, placard designed to be posted in some public place for purposes of commercial announcement or propaganda. Advertising makes wide use of posters, as do charitable and political organizations. In ancient civilizations a simple form of written public announcement was used. The invention of printing and particularly the development of the lithographic process were of paramount importance to poster art. The advertising poster originated in the 1870s. The art of poster design requires, above all, a very clear expression of the idea or product being advanced. It must be visible at a distance and comprehended in one glance, so that lines are generally simple and colors few and bold. Lettering is kept at a minimum. In the 19th and 20th cent. numerous artists designed posters as a sideline to their other work. These include Daumier, Manet, Picasso, Ben Shahn, and Norman Rockwell. Other artists' reputations were based on their poster work. Jules Chéret, Alexandre Steinlen, Alphonse Mucha, and Henri de Toulouse-Lautrec made striking posters advertising entertainments and restaurants. In England outstanding poster designers included Fred Walker, Aubrey Beardsley, William Nicholson and James Pryde (the latter two collaborating under the name "the Beggarstaff Brothers"), Will Owen, and Dudley Hardy. These English artists created highly decorative posters in which the elements of picture and typography remained unified, revealing the influence of East Asian prints. Other leaders in the medium included Ludwig Hohlwein and Paul Scheurich in Germany; the Belgian Hendrik Cassiers; Lev Bakst in Russia; Toyokuni in Japan; and Ramón Casas in Spain. The American poster can be said to have originated with Matt Morgan's circus advertisements (c.1890) and was developed by Edward Penfield, Will H. Bradley, Maxfield Parrish, Howard Chandler Christie, James Montgomery Flagg, Charles Dana Gibson, and Harrison Fisher. The two World War periods produced enormous numbers of political posters; memorable among these were the works of Abram Games in England, Paul Colin in France, and Joseph Binder in the United States. Outstanding poster designers of the 20th cent. are Frank Pick, Gregory Brown, and Clive Gardiner in England; the Americans E. McKnight Kauffer, Paul Rand, Austin Cooper, Pat Keely, Robert Gage, and Peter Max; in France, A. M. Cassandre, Jean Carlu, and Charles Loupot. In Latin America and India posters are widely used in education. There has been an enormous resurgence of interest in posters used for interior decoration in the United States. Among the most popular are reprints of World War I posters; movie advertisements; works by Toulouse-Lautrec, Mucha, and Picasso; and photographs of celebrities and animals.

Opaque watercolour. Also known as poster paint, designer's colour, and body colour, it differs from transparent watercolour in that the pigments are bound by liquid glue, which is used as a thinner. The addition of white pigment lightens the tone and lends opacity. Gouache paints dry to a matte finish and, if desired, without visible brush marks. They can be applied thinly or thickly. A wide range of colours are available, including fluorescent and metallic pigments. The suede finish and crisp lines characteristic of many Indian and Islamic miniature paintings is produced by this medium; it is used in Western screen and fan decoration and was used by modern artists such as Georges Rouault and Paul Klee.

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Eye-catching printed paper announcement or advertisement that is exhibited to promote a product, event, or idea. Posters were popularized by the mid-19th-century invention of lithography, which allowed coloured posters to be produced cheaply and easily. Henri de Toulouse-Lautrec was noted for his poster art, which often advertised Parisian cabaret performers. Poster art flourished with the rise of the Art Nouveau style, as seen in the work of Alphonse Mucha. During World War I posters were used for recruiting and propaganda, and the industrial boom of the early 20th century gave rise to advertising posters for every conceivable product and event. The later rise of film and television advertising led to an eclipse in poster art.

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Archaeologists refer to two different structures as a four-poster . The first is a type of stone setting found uniquely within the British Isles. They date from the Bronze Age and, as the name suggests, usually consist of four stones. Late Bronze Age, Iron Age and Roman four-posters are square arrangements of postholes, around 2-4m square. Some are thought to have supported a raised granary whilst others have been shown to have supported haystacks. Other theories include that they were chicken sheds, workshops, beehives, watchtowers, or platforms for exposing the dead. Four posters are commonly found at hillfort and farm sites.

Bronze Age four posters

It is widely accepted that the four-poster tradition grew out of the recumbent-stone circle tradition of Aberdeenshire at the very start of the Bronze Age. The earliest ancestors of the four-poster are found in the hills north of Inverurie, where gross extremities in the scale of recumbent-stone circles have been found ranging from very large (50 metres diameter) to very small (5 metres diameter). In some of the smallest, the setting consists of six or eight stones, one within 45 degrees of south being only slightly bulkier or special compared with the others. In most of these, a clear rectangle appears stones if only the four largest stones are considered.

The builders of the four-posters -- with their traditions in tow -- travelled south-west, heading for the metal-rich southern regions of Ireland. Around Perthshire, about 200 kilometres away from Aberdeen, an extremely dense cluster of four-posters occurs. Many believe that it was here, in the fertile valleys of Strathtay and Strathmore, that the four-posters became refined into neat squares, averaging 12 square metres in internal area, placed on neat levelled mounds with cists or cremations near the north east stone. Situations were chosen both for their proximity to communities (although this is less the case than with earlier monuments) and for the views they commanded. The south west remains the focal point, with alignments on nearby notches in hills close to the major southern moonset frequently occurring. It should be noted that four-posters are hardly exact astronomical observatories, they should be thought of more as a memento of home for Bronze Age travellers who were ill-equipped to undertake workings on the size of the grand recumbent-stone circles of the soon distant north east.

Quite why there are so many four-posters in Perthshire isn't quite clear. It is possible the tradition was carried on by the local community after the travellers had left, or that long term trade led to the blurring of cultures. Either way, there isn't a single four-poster in the next 300 kilometres to Ireland, suggesting the journeymen picked up pace and hurried down to the cultural crossroads of Machrie Moor on the Isle of Arran, in the vicinity of which several four-posters have been found and excavated. Once on Ireland but outside the south west there are two confirmed four-posters, both on the east coast, suggesting a route down that side of the island, to the region around County Cork, where another proliferation occurs. The radiocarbon dates for remains from this group are later than those for the others in Scotland which confirms the progression in construction.

It seems a reversion to some old habits takes place here, the southern or south west stone becoming higher and thicker, like a miniature recumbent from the recumbent-stone circles. Another stone was added, whilst the two stones furthest away from the 'recumbent' became higher and thinner like the 'portal' stones of the Aberdeenshire circles yet on the wrong side! Eventually, the design was consolidated into what is known as the Munster stone circle tradition.