__X__ was launched by four Harvard students on January 7, 1999. Most of its users were high school and college-going students. It was acquired by Barnes and Noble in 2001 for approx. $3,555,000.
Many teachers accused __X__ of being a cheating tool but __X__ condemns the idea of cheating.
"When your books and teachers don't make sense, we do." is their slogan.
Identify X and explain the title.