Astroturf is a trademark name for the artificial grass developed for the Astrodome after attempts to grow natural grass indoors failed. The name is also used colloquially to refer to other artificial surfaces. In addition to domed stadia, artificial surfaces were also common in the multi-use "cookie cutter" fields popular in the 1960's and 1970's because it wasn't as badly damaged by the heavy use in multipurpose parks.
Artificial surfaces, especially the carpetlike early versions, has a strong effect on playing style. Above all, artificial surfaces tend to reward speed. Bouncing balls bounce higher and more regularly on artificial turf (unless they hit a seam in the surface), which lets fast batters get infield singles on high bouncers in the infield and strong armed infielders to deliberately bounce their throws to the first baseman. Rolling balls aren't slowed as much on Astroturf as they are on grass, which lets fast batters leg out more doubles and triples on balls that roll all the way to the outfield fence and puts a premium on speedy outfielders who can cut the balls off before they get there. Infields in artificially surfaced parks also eliminate the dirt basepaths, having only a small dirt cutout around each base to serve as a sliding area. Because artificial turf gives runners better traction than dirt, this aids base stealing by giving runners a speed edge.
Because of the changes it makes in the game, and because it obviously isn't natural grass, artificial turf evokes strong opinions among fans. Those who favor artificial surfaces enjoy the emphasis on speed over power, or simply the diversity of playing styles. Opponents dislike the turf- and the domed stadia and cookie cutter fields where it was mostly used- as unaesthetic and unnatural. There are also some claims that artificial surfaces, especially poorly maintained ones encouraged by the expense of replacing a ballpark's surface, increase the risk of injuries. Arguments about the pros and cons of Astroturf have diminished in recent years as most parks that used it have been replaced by ones using natural grass, and as the more modern versions have become more grass-like.