Container ships are cargo ship that carry all of their load in truck-size inter modal containers, in a technique called containerization. They are a common means of commercial inter modal freight transport and now carry most seagoing non-bulk cargo.

Container ship capacity is measured in twenty-foot equivalent units (TEU). Typical loads are a mix of 20-foot and 40-foot (2-TEU) ISO-standard containers, with the latter predominant.

Today, about 90% of non-bulk cargo worldwide is transported by container ships, and the largest modern container ships can carry over 21,000 TEU (e.g., 0OCL Hong Kong). Container ships now rival crude oil tankers and bulk carriers as the largest commercial seaborne vessels.