PostScript equipment at the time. This included the fonts that are standard with Windows to this day: Times New Roman (compatible with Times Roman), Arial (compatible with Helvetica) and Courier New (compatible with Courier). In this context, "compatible" means two things. On an aesthetic level, it means that the fonts are similar in appearance. On a functional level, it means that the fonts have the same character widths. This allows documents which have been typeset in one font to be changed to the other, without reflow. Microsoft and Monotype technicians used TrueType's hinting technology to ensure that these fonts did not suffer from the problem of illegibility at low resolutions, which had previously forced the use of bitmapped fonts for screen display. Subsequent advances in technology have introduced first anti-aliasing, which smooths the edges of fonts at the expense of a slight blurring, and more recently subpixel rendering (the Microsoft implementation goes by the name ClearType), which exploits the pixel structure of LCD based displays to increase the apparent resolution of text. Microsoft has heavily marketed ClearType, and sub-pixel rendering techniques for text are now widely used on all platforms. Microsoft also developed a "smart font" technology, named TrueType Open in 1994, later renamed to OpenType in 1996 when it merged support of the Adobe Type 1 glyph outlines. Opentype now contains all of the same functionality of Apple TrueType and Apple TrueType GX. Platform support Macintosh and Microsoft Windows TrueType has long been the most common format for fonts on classic Mac OS, Mac OS X, and Microsoft Windows, although Mac OS X and Microsoft Windows also include native support for Adobe's Type 1 format and the OpenType extension to TrueType (since Mac OS X 10.0 and Windows 2000). While some fonts provided with the new operating systems are now in the OpenType format, most free or inexpensive third-party fonts use plain TrueType. Increasing resolutions and new approaches to screen rendering have reduced the requirement of extensive TrueType hinting. Apple's rendering approach on macOS ignores almost all the hints in a TrueType font, while Microsoft's ClearType ignores many hints, and according to Microsoft, works best with "lightly hinted" fonts. Linux and other platforms The FreeType project of David Turner has created an independent implementation of the TrueType standard (as well as other font standards in FreeType 2). FreeType is included in many Linux distributions. Until May 2010, there were