Analysis of variance (ANOVA) is a collection of statistical models and their associated estimation procedures (such as the “variation” among and between groups) used to analyze the differences among means. ANOVA was developed by the statistician Ronald Fisher. ANOVA is based on the law of total variance, where the observed variance in a particular variable is partitioned into components attributable to different sources of variation. In its simplest form, ANOVA provides a statistical test of whether two or more population means are equal, and therefore generalizes the t-test beyond two means. In other words, the ANOVA is used to test the difference between two or more means.

http://en.wikipedia.org/wiki/Analysis_of_variance

Consider this: Analysis of variance (ANOVA) is a statistical method used to compare the means of three or more groups and determine whether there are statistically significant differences between them. It assesses whether the variability among group means exceeds what would be expected due to random variation alone.