what are all these directories?

[wbar8417]

when i get my ftp working i connect and see lots of directories within my public_html directory. I just want my site in here. What do they all do and which can I delete/move?
some examples:
_private
_vti_bin
_vti_cnf
_cgi_bin

and a bunch of directories with names like that.
Edit:
also what does the .htaccess file do?

 

[bugfinder]

the _<something> directories are from frontpage extensions. If you dont want them, use your cpanel to remove the frontpage extensions, dont just delete them

 

[wbar8417]

oh ok thanks