Sterling silver jump rings are available in 2 basic styles:
Standard jump rings, for connecting items that don't open, and
Closed (or solid) jump rings, which are basically a link for embellishing.
For more sizes of solid links, see bottom of this category.
Sterling silver split rings are popular for attaching charms to charm bracelets, because they're more secure then jump rings. Their overlapping construction (like a tiny key ring) means they are much harder to accidentally pull open. However, they are easy to use: click into any split ring to find the "Related Products" tab, with a link to specialty split ring pliers.