Bridges can be used to replace missing teeth, instantly improving the appearance of your teeth while avoiding the nuisance of wearing dentures.
A secondary benefit to having a bridge is it reduces the additional strain on teeth surrounding a gap. Filling the gap naturally spreads the strain around the mouth, preventing any changes to your bite. However, with the advent of successful dental implants we use bridges less often as they often involve interfering with surrounding teeth whereas implants don't. In the long run implants are often a safer option nowadays.
Bridges are a natural looking long term solution to some extractions or tooth loss. Your dentist can advise you whether this is an option and if so what the costs are likely to be. They will also put together a treatment plan for you.