As Rick asks, what kind of public addressing do you have with your ISPs?
Assuming you have something like a only a single public IPs, or very small public network prefix blocks, and further assuming they differ across ISPs, a most common setup would just use a default static route to each ISP. That would round robin flows, but not care about actual bandwidth usage. I.e. you load share, but real load balancing is hit or miss, though, likely both links would be used.
For failure, using static default routes, you would need to setup SLA monitoring to the next hop for each. Failure of a SLA response would have the router stop using that path (until the SLA works again). During such a failure, assuming, again, each ISP is different IP networks, "in flight" flows, on the lost path, will "break".
As Rick mentions, if you get into dynamic routing with an ISP, they likely will want to use BGP. Some can, as Rick also mentions, support another dynamic routing protocol, but that's, I believe still (?) a bit unusual for ISPs.
As Rick also mentions BGP also supports multiple paths, but, if I remember correctly, not for different BGP ASs (unless you use a "hidden" command). Regardless, most routing protocols, although they will "automatically" deal with failover, also round robin flows. EIGRP does, I recall (?), have the capability to dynamically load balance, but I also recall (?) using it isn't recommended. (Better for something like that would be to use something like Cisco's PfR for such dynamic load balancing.)
