Anxiety is a normal part of a toddler’s emotional and cognitive development. As a toddler becomes more aware of his surroundings and how things work, he can develop fears. He now is learning that sometimes things are not good.  For instance, let’s say your child suddenly becomes very fearful of the vacuum cleaner when it never bothered him before. More than likely, his fear was triggered by a particular incident. While he may not be able to fully understand what that noisy vacuum cleaner does, he knows that it sucked up one of his toys once, and perhaps it could suck him up as well.
Although a toddler’s cognitive skills are rapidly advancing, they still cannot distinguish real from “make-believe”. The combination often results in a toddler conjuring up scary images and scenarios and linking them to everyday things. The dog next door may suddenly become the Big Bad Wolf from his bedtime story.   
There are many forms of anxiety that a toddler can experience; separation anxiety, stranger anxiety, fears of particular items. Some children will develop a few, some will develop many, and some will develop none. This is a normal part of a toddler’s growth and in time, they will pass.