"Look forward" Vs "Looking forward"

"Look forward" Vs "Looking forward"

The word "to" in this phrase may be confusing because it is usually used to introduce a verb, as in "want to", "have to", etc.

Even though saying "I want to hear from you" is completely correct, "to look forward to" employs a different pattern:

I look forward to (a thing you would like to happen)

Obviousely, "hear" is not a thing, so it wouldnt make much sense to "to look forward to hear from you". The thing you are looking forward to is "hearing from you":

I look forward to hearing from you   (correct)
I look forward to hear from you         (wrong)

As for the question wether to use:

"I look forward to" or "I am looking forward to"

Some people consider the two completely interchangeable, but most find the phrase with "look forward to" somewhat formal and best suited for formal cerrespondence, whereas "to be looking forward to" is more informal and friendly:

I look forward to hearing from you       (correct in formal writing)
I am looking forward to hearing from you     (correct in informal context).


Source: "Guide to Most Common Mistakes in English"