Titanic was the second ship of what ocean-liner class?

Titanic was the second ship of the Olympic class. The class was a trio of huge British ocean liners built by Harland and Wolff for the White Star Line in the early 20th century.

RMS Olympic was the lead ship, launched in 1910 and entering service in 1911. Titanic followed as the second vessel, launched in 1911 and making her maiden voyage in April 1912. Britannic was the third ship; she later served as a hospital ship during the First World War.

The Olympic-class liners were designed to compete through size, comfort, and luxury rather than record-breaking speed. Olympic and Titanic were nearly identical, though Titanic included design changes such as larger passenger spaces and enclosed sections of promenade deck. Those modifications gave Titanic a slightly higher gross tonnage than Olympic.

A common mix-up is confusing the Olympic class with Cunard's Lusitania and Mauretania, which belonged to a different pair of liners. Titanic was also not the largest class of ships ever built, but she was briefly the world's largest ship when she entered service.