The numbers you may have seen in people's signatures or the classifieds are there to show how many animals of each sex someone has.
The first number is the amount of males - 1.0.0 = 1 male
The second number is females - 1.2.0 - 1 male and 2 females
The third number is juvenile/unknown sex - 1.2.1 - 1 male, 2 female, 1 unknown
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1.0.0 Common Boa Constrictor
0.1.0 Western Hognoses
1.0.1 Bearded Dragons
0.1.0 German Giant x Hypo Bearded Dragon
0.0.1 Bosc Monitor