Emacs editing by column

For example here is the text I want to edit:

foo
foo
foo

And here is the text result I want to have:

bar foo
bar foo
bar foo

Use rectangles (as mentioned in another answer). 

The explicit directions for that are:

1. goto first line, first column
2. Ctrl-Space
3. goto last line (first column)
4. Ctrl-x r t bar space RET