Perhaps one of the greatest electric typewriter series of all time. (That is, unsubstantiated, unresearched opinion.)

The Selectric lived from 1961 - 1986 approx, when phased out by IBM Wheelwriter daisy-wheel typewriters. Wheelwriters come with microprocessors and limited ROM/RAM setups. I believe the earliest ones could memorize a page or so of data; the latest have primitive non-WYSIWYG PC-DOS-WordPerfect type word processors on a tiny monitor, and have lower-density floppies interchangeable with PC-DOS.

Selectrics were revolutionary in that most previous typewriters, including the contemporary IBM Model A/B/C/D/Executive line, have a moveable platen. Think back to Snoopy moving the "shuttle" back and forth on his toy typewriter. Selectrics move the print head, not the platen. The result: smooth, non-jerky typing which does not require the typist to remove his/her hands from the keyboard.

The print head is a small metallic ball, nicknamed by many the "golf ball." The golf ball is studded with the characters of a particular font (usually a variation of Courier, as on a fixed-font typewriter.) Golf balls are very easy to replace, compared to disassembling a typewriter based on a direct-strike, hammer, moveable platen setup. They snap out by pulling a latch on the top of the ball. Early models like the original 71 have traditional carbon or ink tape spools, but later models have cartridges. From personal experience, replacement of model 71 ribbons is a major pain.

Selectrics came in a few different incarnations during their life-span.

Model 71 - Original "scalloped" design
Model 72 - "Scalloped" design plus cartridge ink spools (no more broken spools stuck in the print head.)
Model II (1973) - New, flattened keyboard design, enhanced cartridge for greater ease
Model II Correcting - Keyboard input correction
Model III -- Last incarnation -- New guided paper input system, redesigned cartridge, redesigned keyboard.

Selectrics of any stripe make great tools for the budding poet or novelist, or just as a conversational piece. Diligent thrift store or garage sale scouting will find low-cost or free units, usually in very good cosmetic, mechanically near perfect condition. Ask, and don't be suprised to find a good or free deal.

Perhaps the only caveat is finding both parts and ribbons. Yet, these can be found in junk piles; office supply stores stock series II and III supplies. Model 71 and 72 bits can be purchased either online or through junk bin searching. However, Selectrics appear to be built for Mutually Assured Destruction.