copy & paste objects

ive been looking on the internet for a LONG while now and my eyes are starting to burn. HOW DO I COPY AND PASTE OBJECTS!?!?!?!?!?!

Try “shift + d” for a duplicate or “alt + d” for a linked duplicate.

what if im trying to copy it and paste it in another file?

file->append, browse for the blend file, treat it like a directory, go into objects and select yours by name.
make sure the append button is checked so it actually makes a copy, not a link to your original file.