Arial gives the illusion of being a very plain typeface. It seems to be basic to a fault, simple lines in simple shapes that anyone can read. And since it is probably the most ubiquitous sans serif typeface on the web and in print, we are all used to reading it.
It has a no-nonsense industrial look, though details like the diagonally cut ends of some strokes soften its effect. It can appear, in a paragraph, a little like a bundle of sticks and round balls that have come together to make up letters.
Arial was originally designed in 1982 by Robin Nicholas of Monotype, as a sans serif typeface for low-resolution laser printers; it was later developed, with Patricia Saunders of the Monotype drawing office, into a full typeface family, which Microsoft licensed as one of the core set of fonts for Windows 3.1 in 1992. A lot of attention was put into the hinting of this typeface. Hinting is adding code to the font so that its letter shapes will be clear on screens even at small sizes.
The original Arial family includes Arial, Arial Narrow (useful for fitting copy into very narrow columns), Arial Black, and Arial Rounded MT Bold.