Modern wall art, and which modern you mean.

Three things called modern

• Modernism — the art movement, roughly 1860 to 1970. Mondrian, Matisse, Rothko. If this is what you mean, you are after prints of existing works, not new art.
• Mid-century modern — a specific design period, 1945 to 1965. Flat geometric shapes, hard edges, a particular palette of mustard, teal, burnt orange and walnut. Narrow and recognisable. There is a whole page on what that palette actually was.
• Contemporary — art being made now, for rooms as they are now. This is what most people searching “modern wall art” actually want: clean, uncluttered, not fussy, not traditional.

What contemporary looks like in practice

Generous negative space. A restricted palette — three or four colours, rarely more. Soft or hard-edged abstract forms rather than representational scenes. Matte finish rather than gloss. No ornate frame; a thin oak or black surround, or none.

The common thread is restraint. A contemporary print is usually doing less than a traditional one, and the room is what fills the gap.

Why it is the easy choice

Abstract, uncluttered art has no subject to argue with the room. A landscape has a horizon and a mood; a botanical illustration has an era attached to it; an abstract in the right three colours simply sits there and works. That is why it is the most forgiving thing to buy for a room you have not finished decorating — the reasoning is on the abstract page.

The one thing contemporary art still gets wrong is scale. Restraint at the wrong size reads as emptiness. See large wall art for the sizing.