A self-similar object is exactly or approximately similar to a part of itself (Wikipedia 2006).
Examples:
Self-similarity is an important aspect of the design of computer networks, as typical network traffic has self-similar properties (Wikipedia 2006).
Example: In teletraffic engineering, packet switched data traffic patterns are statistically self-similar (Wikipedia 2006). This property emphasises that simple models using the Poisson distribution are inaccurate (Wikipedia 2006). Networks that are designed using the Poisson distribution without taking self-similarity into account are likely to function in unexpected ways.
Self-similarity is a typical property of fractals.
Exercise: In the following diagrams, say whether they are self-similar or not. Answer
References:
Wikipedia. "Self-similarity", Wikimedia Foundation Inc, http://en.wikipedia.org/wiki/Self-similarity, Last accessed 11 February 2006.
Brandon Hodgson