have aliens really visited earth?

is it true that aliens have visited earth.?
Is any proof available?
where is probably the home of aliens?
Do aliens really have spaceships like those which we see in movies?

Answer1:
practicaly it is impossible...it is just our imazination but but acc. to a sciencetist who is member of us navy centre area 51 told that aliens visted earth and have contect with us scientist....i donn't know the name of that man but it might be happend as now it is 21st century.........