The Spectator (1711-1712 and 1714) was a weekly magazine written by Joseph Addison and Richard Steele, which followed an earlier weekly magazine, also written by Addison and Steele, called The Tatler. While The Tatler was designed, chiefly by Steele, to discuss moral issues in light, somewhat gentle and humorous essays, The Spectator focused more consistently on political, philosophical, religious and literary issues, for the most part from what we would now call a liberal perspective (in the 18thC., the Whigs) as opposed to the more conservative political party, the Tories. Despite the political focus, however, the characters who form the Spectator Club are not viciously satirized--rather, like the essays in The Tatler, the satire is relatively mild but, from a political perspective, pointed enough so that readers understood that Tories should not be running the government.
The most memorable member of the club is Sir Roger de Coverley, a confused member of the landed gentry whose political, philosophical and religious ideas are about a hundered years behind the times. He represents Addison and Steele's version of the typical Tory of the mid-18thC.--too conservative, old-fashioned, clinging to outmoded moral beliefs, unsympathetic to the plight of the comman man, blissfully unaware of economic and social changes in society.
The remainder of the club members included Mr. Spectator, who gave opinions on many issues (for example, politics, education, morality, literature); the Templar--all things related to education, legal matters and literature; Will Honeycomb--social life, including fashion; the Clergyman--religion and moral issues; Sir Andrew Freeport--business and economic matters (he was the opposite of Sir Roger); and Captain Sentry--military matters. In short, some member of the club could and would discuss virtually every meaningful aspect of 18thC. British society.
From a literary perspective, the significance of The Spectator is that Addison, who wrote most of the essays, perfected the essay as a way to discuss important social, political, and religious issues in what Dr. Johnson called the "middle style," aimed at an educated but not scholarly readership.