Generally recommended to limit max charge to 80% if that covers your needs, charging to 90% or 100% only when necessary. Also I believe advice is to try to keep it above ~30%.
All rechargable batteries can physically and chemically wear out with repeated cycles, resulting in capacity loss. The majority of the wear and tear happens a the extreme ends; fully charged and fully discharged. By keeping away from the extremes, you minimize the wear and prolong battery life.