What happened to wilson on home improvement?

In the 1991 to 1999 comedy Home Improvement, Wilson is Tim Taylor's neighbor and confidant. He frequently gives advice to all members of the Taylor family and often recites words of wisdom, famous quotes, or historical examples to Tim. As a common joke, Tim would often dismember these phrases when trying to repeat them (with the effect of making the advice unintelligible or simply absurd). In the television comedy Home Improvement, from 1991 to 1999; to be more exact, Wilson appeared partially, due to an ordinary joke that was only seen on the top of his face while talking to his neighbor since the other side of a tall fence.

If you've ever watched Home Improvement, you've probably wondered why Wilson, the Taylor family's neighbor, never shows his face.