Italics are probably the most common form of typographic emphasis and is used in both text and display settings. True-drawn italics are usually a unique and separate design from their Roman brethren. Aldus Manutius, a commercial printer, was looking for a way to fit more type onto a page and to reduce the price of his low-cost editions.
Obliques are slanted versions of their roman companions with few or no design changes. Helvetic Italic, for example, is not a real cursive italic but an oblique.
Creating obliques by slanting roman characters is not encouraged, as it inevitably distorts the shapes of the letters in unpleasant if subtle ways. It is preferable to use a designed oblique if it is available.
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