There are over 42,000 species of spiders identified worldwide. Taxonomically, all belong to the kingdom animalia, phylum arthropoda, class arachnida, and order araneae. Within this order, there 110 different spider families and over 3800 genera. Spiders that are black with white rings around their legs are likely members of one of two different spider genera, Eresus or Phidippus.
Genus Eresus: Males
There are 96 different species of spiders within the family Eresidae, commonly known as the velvet spiders. Within this family are spiders of the genus Eresus, containing the species Eresus sandaliatus, Eresus kollari and Eresus cinnaberinus. The males of these species have a bright orange abdominal region, with black spots. Most of the rest of the spider's body is black, but the legs have distinct white rings.
Genus Eresus: Females
The females of the Eresus species do not have the orange colouration, and are almost entirely black. They may also have white rings around the legs, but the rings are not as distinct as in the males. Females are slightly larger, which is almost always the case for spiders.
If you had to guess the species of a spider based on a description of black with white rings around the legs, Phidippus audax would probably be your best guess. This is commonly known as the "bold jumping spider" or the "daring jumping spider." ("Audax" comes from the same Latin root as "audacious.") The white bands on the legs are more distinctive in the males of this species than the female.
Other Phidippus Species
Some other Phiddippus species can also be predominantly black with white leg bands, including Phidippus clarus, Phidippus regius, Phidippus clarus, Phidippus purpuratus, and Phidippus borealis. The markings and colouration in these different species vary, and the distinct white bands on an otherwise black body is not as pronounced as in the audax species, especially males of the species.