the lord of the rings - Was the "Eye of Sauron" Sauron's actual physical form?

During the time frame of the Lord of the Rings, was the Eye of Sauron Sauron's actual physical form? If not, what form did he have?

Answer

No, according to Tolkien himself Sauron had a physical form in the third age:

...in a tale which allows the incarnation of great spirits in a physical and destructible form their power must be far greater when actually physically present. ... Sauron should be thought of as very terrible. The form that he took was that of a man of more than human stature, but not gigantic. ~ The Letters of J. R. R. Tolkien

The depiction of the Eye of Sauron shown in the cinematic releases of LOTR is not wholly absent in the books; Tolkien gives a description of it in The Fellowship of the Ring when Frodo spots it from the Mirror of Galadriel:

But suddenly the Mirror went altogether dark, as dark as if a hole had opened in the world of sight, and Frodo looked into emptiness. In the black abyss there appeared a single Eye that slowly grew, until it filled nearly all the Mirror. So terrible was it that Frodo stood rooted, unable to cry out or to withdraw his gaze. The Eye was rimmed with fire, but was itself glazed, yellow as a cat's, watchful and intent, and the black slit of its pupil opened on a pit, a window into nothing.

Despite the description, the Eye was only perceived by very few people in Middle-Earth, and did not have a physical worldly form, unlike Sauron.

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In The Hobbit: The Desolation of Smaug, the pupil of the great eye is shown to be the fiery silhouette of Sauron.