Adobe Illustrator is a vector-based drawing program developed and marketed by Adobe Systems.

Versions 1–88

Adobe Illustrator was first developed for the Apple Macintosh in 1986 (shipping in January 1987) as a commercialization of Adobe's in-house font development software and PostScript file format. Adobe Illustrator is the companion product of Adobe Photoshop. Photoshop is primarily geared toward digital photo manipulation and photorealistic styles of computer illustration, while Illustrator provides results in the typesetting and logo graphic areas of design. Early magazine ads (featured in graphic design trade magazines such as Communication Arts) referred to the product as "the Adobe Illustrator". Illustrator 88 was released in 1988 and introduced many new tools and features.

Versions 2–5

Although Adobe developed Illustrator primarily for the Macintosh during its first decade, it sporadically supported other platforms. In the early 1990s, Adobe released versions of Illustrator for NeXT, Silicon Graphics IRIX, and Sun Solaris platforms, but they were discontinued due to poor market acceptance. The first version of Illustrator for Microsoft Windows, version 2.0, was released in early 1989, but it was a flop. The next Windows version, version 4.0, was widely criticized as being too similar to Illustrator 1.1 instead of the Macintosh 3.0 version, and certainly not the equal of Windows' most popular illustration package CorelDraw. (Note that there were no versions 2.0 or 4.0 for the Macintosh - although the second release for the Mac was titled Illustrator 88 - the year of its release.) Version 4 was, however the first version of Illustrator to support editing in preview mode, which did not appear in a Macintosh version until 5.0 in 1993.

Versions 6–10

With the introduction of Illustrator 6 in 1996, Adobe made critical changes in the user interface with regards to path editing (and also to converge on the same user interface as Adobe Photoshop), and many users opted not to upgrade. Illustrator also began to support TrueType, making the "font wars" between PostScript Type 1 and TrueType largely moot. Like Photoshop, Illustrator also began supporting plug-ins, greatly and quickly extending its abilities.

With true ports of the Macintosh versions to Windows starting with version 7 in 1997, designers could finally standardize on Illustrator. Corel did port CorelDRAW 6.0 to the Macintosh in late 1996, but it was received as too little, too late. Aldus ported FreeHand to Windows but it was not the equal of Illustrator.Fact: date=October 2008 Adobe bought Aldus in 1994 for PageMaker, and as part of the transaction it sold FreeHand to Macromedia (which was later acquired by Adobe). Clarifying difference in strengths between Photoshop and Illustrator with the rise of the Internet, Illustrator was enhanced to support Web publishing, rasterization previewing, PDF, and SVG. Version 9 included a tracing feature, similar to that within Adobe's discontinued product Streamline.