Eyelash extensions are single synthetic lashes applied directly to the natural lash, close to but not touching the lash line with semi-permanent bonding adhesive and leaving the eyelashes and eyelids to move freely.  The whole process takes about 1 to 3 hours depending on how many lashes are applied.  

I only use synthetic mink; which is man made fibers, designed to imitate real mink fur.  They are very fine, soft and silky.  Good thing about synthetic mink is that when you get them wet, they won't lose their curl however with real mink fur lashes will lose their curl and would have to use a curler to curl them back up