Definition - What does G3 mean?
G3 is Apple’s name for its PowerPC 750 chip. Apples calls G3 the third generation of its advanced processor technology.
The G3 chip was used in a series of personal computers designed, manufactured and sold by Apple between 1997 and 1999. The chips were referred to as PowerMacintosh G3, beige G3 or platinum G3 (referring the color of each chip's case). These replaced several other computer models, specifically the 7300, 8600 and 9600.
Techopedia explains G3
Apple also manufactured a PowerBook G3 laptop computer between 1997 and 2000 using the PowerPC 740 and PowerPC 750 microprocessors. These processors were the first specifically optimized for the Mac OS.
Performance enhancements to this microprocessor were instrumental in reducing the usefulness of clock speed in comparing computer performance. In fact, some computers with PowerPC processors outperformed Pentium II-based systems, as well as others with higher clock speeds. Performance was based on tests using 15 Adobe Photoshop filters. A 266 MHz Power Macintosh G3 was 30 percent faster, on average, than a similar 266 MHz Pentium II system.