Tennis circa 1600 was a game played by those of the Court (Tennis Court), namely those of the aristocracy. Performed in full dress retinue, wearing silken slippers, and played only by men, the game was often observed by ladies of the gallery, protected always from the elements by a full awning of some sort, who, when the game ball was hit into the stands, had the option of returning it to the player and, if she so desired, returning with it her handkerchief, thus providing the fortunate prince (earl, duke, etc.) the opportunity of an excuse to meet this lady again at a time and place of their choosing. It was very much a 'peacock' sport, where the men would preen for the lady observers.

The following is UNVERIFIED! by me, but interesting none the less.

Shakespeare's works contain six references to tennis:

1. Hamlet - Here the tennis reference occurs when Polonius is giving instructions to Reynaldo on how to spy out his son's conduct in Paris
2. Second Part of King Henry - "But that the tennis-court-keeper knows better than I; for it is a low ebb of linen with thee when thou keepest not racket there; as thou hast not done a great while..."
3. Henry VIII - Here Sir Thomas Lovell announces Englishmen must renounce "the faith they have in tennis and tall stockings" referring to the popularity each has in France at that time.
4. Much Ado About Nothing - Here tennis is only a metaphorical reference to Benedick's improved appearance. He is shaven close, not bearded, and as a result, "the old ornament of his cheek hath already stuffed tennis-balls."
5. Pericles - "A man whom both the waters and the wind In that vast tennis-court hath made the ball For them to play upon..."
6. Henry V - "When we have matched our rackets to these balls,

We will, in France, by God's grace, play a set

Shall strike his father's crown into the hazard.

Tell him he hath made a match with such a wrangler

That all the courts of France will be disturbed..."

Very early on, the ball was a wad of hair, wool, or cork wrapped in string and cloth or leather, then in later years, hand-stitched in felt to look something like a modern baseball.

By the year 1500, a wooden frame racquet strung with sheep gut was in common use, as was a cork-cored ball weighing around three ounces. The early tennis courts were quite different from the modern "lawn tennis" court most of us are used to. The early game matured into what is now called "real tennis," and England's Hampton Court, built in 1625, is still used today. Only a handful of such courts remain. It's a narrow, indoor court where the ball is played off walls that include a number of openings and oddly angled surfaces toward which the players aim for various strategic purposes. The net is five feet high on the ends, but three feet in the middle, creating a pronounced droop.

The game's popularity dwindled almost to zero during the 1700s, but in 1850, Charles Goodyear invented a vulcanization process for rubber, and during the 1850s, players began to experiment with using the bouncier rubber balls outdoors on grass. An outdoor game was, of course, completely different from an indoor game played off walls, so several new sets of rules were formulated.

http://tennis.miningco.com/library/weekly/aa041101.htm