EServer

eServer refers to a family of computers produced by IBM.

The family of products consists of:

• iSeries -- Midsize (midrange) systems. Formerly AS/400, now i5.
• zSeries -- Mainframe systems, formerly S/390.
• pSeries -- Midsize unix systems, formerly RS/6000.
• xSeries -- Server systems based on x86 architecture.

Citing data from Gartner and IDC, a 2005 IT Jungle Article showed that HP, IBM, Unix and Windows were tied for the global server market.