Nick Jr. is a programming block aired by the Nickelodeon channel on weekday mornings. The majority of Nickelodeon's preschool series have been included as part of the block, though some air exclusively on the channel of the same name (which replaced Noggin).
The block was launched on January 4, 1988. The majority of the programming included as part of the block were not original series. The first original series was Eureeka's Castle, which premiered in 1989. The first short-form series was Hocle and Stoty, which ran from 1994 until 1996.
The block has gone through many redesigns since its initial launch (along with numerous minor changes to bumper styles and slogans). Most redesigns introduced new mascots, while some simply changed the overall appearance of the block's commercials.
The block has had several mascots over the course of its run. Its first mascot was Face (who appeared on advertisements and bumpers from 1994 until 2004. He was replaced by Piper O'Possum, who appeared on the block from 2004 until 2007. There was no mascot from 2007 until 2009. The Moose and Zee characters acted as "hosts" of both the block and the channel from 2009 until 2012. The block has abandoned the use of mascots, and uses characters from original series on commercials and bumpers in place of them.