Pentium family of computer chips
The Pentium family are lineal descendants of intel's earlier successful designs, the intel 4004, intel 8008, intel 8080, intel 8086, intel 80286, intel 386 and intel 486 brands. Where the 4004, 8008 and 8080 had less than ten thousand transistors incorporated on their surface the earliest pentiums had over a million transistors.
Competing manufacturers had brought out pin compatible chips -- chips that executed the same instruction set, and could be plugged in, in place of intel chips, and had given their chips the same names as the intel chips. Rather than naming their next chip in the series the intel 80586 intel chose to pick a made name that could be trade-marked. They chose "pentium", so no competitor could give a competing chip the same name.
The most successful rival to the earliest Pentiums was the AMD K6 series.
Rather than choose new names for the chips that succeeded the Pentium, they named the succeeding chips, the Pentium 2, Pentium 3 and Pentium 4. The original Pentiums are now called the Pentium 1 to distinguish them from their successors.
After Pentium 4, last generation of Pentium family named Pentium D was released in 2005 until 2008. Clock rate ranged from 2.66 GHz to 3.73 GHz.