yourself or "by" yourself??

[kenny1999]

it is common to hear that "do it yourself.."

does it mean that you should do something on your own?

how about "by yourself"?

but i must have heard about something like "by yourself..." "by myself.. " ...

what is the difference by adding "by" ?

In fact, Precise English is very important for my job............ I need true grammar about this. THanks

[Whoknows]

Yourself is the reflexive form of you. It has many uses that you can find in the dictionary. But in your example either is correct because in 'Do it yourself' the ' by' is understood. They both mean to do it unassisted.

At least that is my take on it.