Well, I don't need to remember all of them, I can just remember the ones that I find convenient and use them. In the end the validator will tell me whether I me

Well, I don't need to remember all of them, I can just remember the ones that I find convenient and use them. In the end the validator will tell me whether I messed something up. While you're right that I won't write <html>, <head> very often I can very well imagine that skipping </td> and </tr> is convenient in many situations.