Does backing up an iphone on to my mac take up computer space?

I had 100 GB of free space but after i backed up my phone, i had less then one GB

Of course backing up takes up space, as the data is stored locally on your computer. However, there's no reason for it to take up 100GB of your drive as the storage sizes of iPhones are only 64GB. There must be some other program installed, media downloaded, etc that is consuming all of your storage.
Check anything recently installed/downloaded to see if it is using more space that it should be.