To hearing vs to hear

English as a Second Language English Vocabulary, Grammar and Idioms
1

Hello,

I would like to know why the following sentences have the verb “to hear” in different forms:

1- I look forward to hearing from you;
2- It was so great to hear from you.

Thanks a lot in advance. Cheers!

2

Hi ,

The structure is: look forward to doing.

Alan

3

Thank you, Alan.