What qualifies as an alias?

I am a recent college graduate who is looking to submit an sf86 form for an enlistment position. My question is what qualifies as an alias? I tend to not use my real name whenever possible in filling out online applications for things such as email, skype, ect… (ie. I will use John Smith or something similar). Do I list those names?

You should list those names that you sign official documents with or names that friends, family or co-workers use in you interactions. And of course all legal names if additional to your birth name.