From Diablo Wiki
Cold is one of the types of elemental damage in Diablo III. It is blue in appearance and has a secondary effect of chilling or freezing targets. Chilled enemies are slowed, while frozen enemies are locked motionless for some duration of time.
Cold damage is dealt by a wide variety of weapons, as well as skills.
Monsters may deal cold damage as well, and it is most commonly seen on the Frozen Elite Affix, which damages and freezes players and minions in range of an exploding ice core.
Cold resistance mitigates the damage taken by cold attacks. The freez time can be reduced or canceled by various skills, or modifiers that reduce crowd control effects.
Cold Secondary Effects
Secondary effects were removed from all damage types and critical hits during Diablo 3's development. All save for Cold damage, which retained a chilling or freezing property, at the cost of slightly lower damage. Some weapons and other properties have a slowing or freezing effect that may not be related to cold damage.