Introductory It

A :     To understand this lesson is easy.

B :     It    is easy to understand this lesson.

•          In this pattern, it has no meaning. It is used only to fill the subject position in the sentence. Thus, it is called introductory “it”.

•          A and B mean the same thing, but sentence B is more common and useful than A. A was introduced mainly to make the meaning of B easier to understand.  

Example of Introductory “it” :

•          To watch musical programs is pleasant.

•          It is pleasant to watch musical program.

•          To play football must be fun.

•          It is fun to play football