Pit

II. A compartment or place partitioned off for the separate accommodation of people or animals.

8. a. A seated compartment in a theatre, at first specially for ladies; often qualified, as front-, private-, side-, stage-, upper-, etc. In pl. collectively for a distinct part of the auditorium.
(As box, when this sense arose, had not acquired the sense of a large wooden chest, but was chiefly an apothecary's pill box or ointment pot, or perhaps a ‘jewel-box’, its transference to the theatrical use was more remarkable than it seems to us with our notions of large ‘boxes’ for goods. Could it be at first humorous or jocular, with some reference to ‘casket’, ‘jewel box’, or ‘box of ointment very precious’?)

1609 DEKKER Gull's Horn-bk., I mean not into the lords roome, which is now but the stages suburbs. No, these boxes..are contemptibly thrust into the reare. 1632 MASSINGER City Mad. II. ii, (Anne) The private box ta'en up at a new play For me and my retinue. 1667 PEPYS Diary (1877) V. 60 We were forced to go into one of the upper boxes at 4s. a piece. 1755 JOHNSON Dict., Box, the seats in the playhouse where the ladies are placed. 1779 SHERIDAN Critic I. i. 443 Applications from all quarters for my interest..from ladies to get boxes. a1845 HOOD United Fam. xvi, Nine crowded in a private box. 1881 Daily News 12 Sept. 2/3 The auditorium, the boxes, upper circle, and gallery.

During the seventeenth, eighteenth, and nineteenth centuries, the theatrical space was divided into three and sometimes four and five general seating areas--the pit, the boxes, the galleries (in different cases, upper and lower), and sometimes stage seating. Each seating area occupied a distinct price point, and therefore distinct classes of people occupied each. According to Joanna Phillips, Restoration seating prices remained fairly stable until the 18th century:

PIT, or main floor - half crown, sunken below ground level, benches appeared after 1660, flaps (hinged sections of benches) used instead of aisles to increase seating capacity, floor of the auditorium was raked, pit took various shapes-- semicircle, broad fan, rectangle, magnet shape, entered by doors in the side walls near the stage

Galleries - 18 pence for middle gallery, 1 shilling for upper gallery rose above the boxes, usually in the back of the theatre only

Boxes - 4 shillings, multitiered boxes rose above the pit on all three sides, some with as many as 7 rows of seats per box.

Different classes and personalities tended to occupy each form of seating. According to Rupert Speirs, box seating "was the most expensive area of the auditorium, a box costing 4 shillings (20p). Boxes were used by people of high class and mostly by ladies and their protective husbands, though women often went to the playhouses unattended. A gallant might approach the boxes in an attempt to charm the lady of his choice, but it was certainly no place for him to spend the entire performance. In some theatres approach to the boxes was in fact quite easy as the raked pit brought the boxes and pit almost level. Sparkish in The Country Wife will not sit in the boxes as he wants to be thought of as a theatre critic not just an admirer of fashion: 'SPARK. Pshaw! I'll leave Harcourt with you in the box to entertain you, and that's as good; / if I sat in the box, I should be thought no judge but of trimmings' (here 'trimmings' means fashions. Act ii, Scene i.)."

You can see the haughty distinction of box audiences even in the early 19th century in Cruickshank's 1836 caricature of the theatrical audience.