On March 16 1995, Madonna’s The Immaculate Collection was certified 6x platinum (6 million units) in the USA.

Review by Stephen Thomas Erlewine (allmusic.com):

On the surface, the single-disc hits compilation The Immaculate Collection appears to be a definitive retrospective of Madonna’s heyday in the ’80s. After all, it features 17 of Madonna’s greatest hits, from Holiday and Like a Virgin to Like a Prayer and Vogue. However, looks can be deceiving. It’s true that The Immaculate Collection contains the bulk of Madonna’s hits, but there are several big hits that aren’t present, including Angel, Dress You Up, True Blue, Who’s That Girl and Causing a Commotion. The songs that are included are frequently altered. Everything on the collection is remastered in Q-sound, which gives an exaggerated sense of stereo separation that often distorts the original intent of the recordings. Furthermore, several songs are faster than their original versions and some are faded out earlier than either their single or album versions, while others are segued together. In other words, while all the hits are present, they’re simply not in their correct versions. Nevertheless, The Immaculate Collection remains a necessary purchase, because it captures everything Madonna is about and it proves that she was one of the finest singles artists of the ’80s. Until the original single versions are compiled on another album, The Immaculate Collection is the closest thing to a definitive retrospective.