Some visual characteristics common to the entire Century family of typefaces are the following:
For lower case type, the curl ending in a ball terminal on top of letter c. Ball terminal on hook of f, ear of g, and tail of j.
For upper case type, the curled tail on the capital R and reflexive curled tail on the capital Q. Prominent top spur on capital C.
For figures, the curl ending in a ball terminal on both tails of 3, and on single tail of 2, 5, 6 and 9.
Century Oldstyle has oldstyle serifs, meaning that the upper serifs of the ascending lower case letters are slanted instead of straight (b,d,i,k,l), and it lacks the curled tail in the capital R and the long, straight vertical serifs in the capital T.
More specific characteristics are listed within each typeface under Typefaces.