You may have noticed that many images on Art UK, in fact nearly a thousand, have the terms 'verso' or 'recto' as part of their title. What does this mean?

Recto from the Latin rectum, meaning right or correct, and verso from versus, meaning turned or changed, are traditionally used to describe the front and back of a painting or drawing. The recto is the front or main image, the verso or back being a secondary image. So what sort of pictures have paintings on both sides?

Unlike familiar easel paintings, which are intended to be hung on a wall and seen from only one side, many of the earliest paintings in the Western tradition were in fact double-sided.

The Crucifixion with the Virgin and Saint John; Saint Anthony Abbot at the Foot of the Cross

They were free-standing physical objects to be seen from both sides. Indeed the earliest known paintings on canvas are double-sided religious processional banners, such as the one attributed to Spinello Aretino in the V&A, dating from around 1370.

Saint Anthony Abbot and Saint Eligius with Two Pairs of Kneeling Worshippers

Following in this tradition are the many nineteenth- and early twentieth-century church banners which survive, and the related Sunday School and teetotal movement banners, such as those in the wonderful collection of the Englesea Brook Chapel and Museum, celebrating Methodist history. Both sides of many of these banners are shown on Art UK – for example Nottingham's Onward Band of Hope from Portland Road, Selston, as are those of the trade union banners in the People's History Museum in Manchester.

Banner from the Onward Band of Hope, Portland Road, Selston

National Union of Railwaymen Smithfield Branch Banner

Shop and pub signs are another form of double-sided artwork. A few of these are to be found in local history collections, such as those for 'The Turk's Head' in Hertford Museum and the 'Ship Tavern' in Gwynedd Museum and Art Gallery.

More unusual is the artist Charles Shannon's At the Sign of the Dial in Aberdeen Art Gallery, made for the Vale Press, run by Shannon and Charles Ricketts.

Indoors, a few items of furniture lend themselves to artistic painted decoration on both sides, especially screens (against draughts and the fire). Both sides are not always illustrated, but Matthew Smith's screen Leda and the Swan illustrates clearly that the main side is described as the 'recto' and the secondary side, the 'verso'.

Mary Potter's Night and Day in Manchester Art Gallery is another example of a double-sided artist's screen.

In more conventional Western art, the most common early examples of double-sided paintings are altarpieces. Set above or behind the altar of a church as the focus of worship, these are often complex structures, incorporating sculpture, elaborate carving and gilding and many separate images on one or more themes.

The winged altarpiece originated in Northern Europe in the early fourteenth century. The hinged wings could be open or closed and were painted on both sides allowing different images to be displayed at different times, according to liturgical demands. The open altarpiece displays the finest work; the backs, or verso, of the closed wings are sometimes in monochrome.

British collections are full of fine examples: at Upton House an altarpiece by Hieronymus Bosch and his workshop shows the Adoration of the Magi and Saint Joseph on the inside and, in contrast, when closed a vignette of Christ before Pilate.

Christ before Pilate, Set within Grisailles of the Forces of Evil

The monochrome backs of the wings of the Bowes Museum's 'Crucifixion' altarpiece by the Master of the Virgo inter Virgines were so little regarded that there are visible strengthening wood blocks, and previous owners' stencil marks and museum labels.

But very many more pictures than altarpieces are painted on both sides. The most common are not finished paintings but sketches and studies for the artist's personal use in the studio. There, reusing the back of a board or canvas for reasons of economy is common practice. Some museums have fascinating collections of such artists' sketches, for example those of William Etty at the Courtauld Gallery and by Alfred Munnings at the Munnings Art Museum, Dedham.

We are currently unable to display this image due to copyright restrictions

Some artists for genuine reasons of poverty regularly painted on both sides of their supports. Most notable is Alfred Wallis, the fisherman painter of St Ives, who late in life used scraps of cardboard for his evocative and strikingly composed visions of the fishing boats and harbours of his Cornish youth.

Being able to see the verso, the backs, of some paintings on Art UK also gives us a rare glimpse of the history of the pictures, as recorded in the inscriptions, labels and museum identity numbers written and pasted over their backs. For example, Robert Sivell's Mother and Child in the McLean Museum and Art Gallery was abandoned unfinished and turned over to use for his lovely The Drawing Book.

There may be other reasons for reuse. Henry Fuseli's A Scene from 'The Wife of Bath's Tale' at Petworth House was discovered in 1957 to have been painted on the back of a fine but partly erased Group of Five Women, perhaps because its content was consider obscene.

Group of Five Women Mocking an Effaced Figure (Falstaff in the Laundry Basket Mocked by Women?)

Marjorie Henry's The Market Hall has on its verso The Street, which was clearly deliberately rejected by the artist but has not stopped it being shown to us today!