Why is HCl considered a strong acid?

Because it feels good when that soothing feeling comes from it flowing through

Hydrochloric acid is in fact a strong acid. Strong acids are strong electrolytes, which, for most purposes, and they are assumed to ionize completely in water. HClionizes completely to hydrogen ions, H + and chloride ions, Cl - ... but don't forget that weak acids only partially ionize in water.