Ant attack...

k the past 2 days I've seen an ant crawling around my computer screen, or the desk, or on my arm.  Is it the same ant every time?  or different ants, and there's ants all around me but I only see 1 at a time.  I can't seem to find where they are coming from but every 10-20 min I see an ant. (ps - these ants are like less than a milimeter in size)