The Ariane 5 uses two solid rocket boosters (SRBs), which can be recovered by parachute if desired. However, unlike (for instance) the space shuttle SRBs, Ariane 5 SRBs are only occasionally recovered, and only when post-flight analysis is necessary due to some sort of anomaly during launch; even when recovered, Ariane 5 boosters are not reused.
Why aren't the Ariane 5 boosters routinely recovered and reused?
The shuttle SRBs weren't really cost-effective to reuse. The nozzles and nozzle boots were replaced completely, as were many other components; the segment casings were deformed by the force of splashdown, and had to be reshaped. Designing the booster for reuse, and inspecting each rebuilt booster thoroughly to be assured that it was safe to use — particularly after the Challenger accident — was likely more expensive in the long run than using a simpler, cheaper, disposable design.
