thanks

"Thanks" is a friendlier way to say "Thank you". Use it with people you know pretty well, like family members, friends, and coworkers who you've spoken with in the past.

(someone) would have (done something)

Whenever you hear "I would have ___", you can always imagine that the sentence ends with "...if ___". For the example above, the speaker is trying to say "I would have remembered even if you hadn't emailed me."

"I would have ___" is used to talk about something that didn't really happen, but you're imagining how things would be different if something different had happened in the past (like if your sister hadn't reminded you of your mom's birthday). You use "would have (done)" whether the action would have happened in the past, or in the future. In the example above, your mother's birthday hasn't come yet, so you say:

I would have remembered!

But you would also say the same thing if your sister mentions that she remind you of your father's birthday six months ago:

I would have remembered that too!

A note on pronunciation: "would have" is usually pronounced "would've". Some English speakers who don't write very well make the mistake of writing this as "would of" instead of "would have".