Do as Your Momma Told You and 'Say Thank You'!
Updated: Jun 9, 2021
Just survived an interview and relieved that your part in the hiring process is done? WRONG! You have one more, very important, step - to send a post-interview thank you note/email.

A vital part of standing above and edging out the rest is rooted in basic manners: acknowledging your gratitude to the interviewers for taking the time to meet with you.
Does it really help?
Yes! In fact many managers use this as a final screening tool to choose their #1. And at the very least, it can't hurt (but it almost always helps).
When do I send it?
Now. Within 24 hours of the interview. Even if you interviewed on Friday at 3pm, ensure you send it before you kick into weekend-mode.
Should it be an email or physical note/card?
It depends. An email is quick, and it's more likely to be received prior to the final hiring decision when you know they're on a tight timeline. On the other-hand, a card is very personable and can demonstrate creativity.
I personally gravitate towards an email - but I've recruited for roles where a physical thank-you card nudged a candidate to the top of the list.
When making your choice consider the industry (IT roles would gravitate towards an email for example), timeline, interviewers (did your interviewer mention she's crafty?), and even your penmanship (stuck in elementary-school style? Stick to digital) when deciding.
What do I say?
This shouldn't be long! In fact the longer it is, the less likely it is to make the impact you're hoping for. Your email/note should include these pieces, in whatever order fits the context of the interview.
Say thank you.
Include a unique antidote from the interview. This can be about the role, or about informal 'chatter' not related to the role at all.
Confirm your excitement for the role and why
Confirm your 'nugget' that makes you a great fit for the role
Finish with your contact information and next steps
It can look something like this:

Who do I send it to?
Everyone in the interview.
Don't have their contact info? At the very least sent the email to whomever set up the interview with you, and ask them to forward to the attendees - and list them by name.
Help - I'm not a creative writer!
Google to the rescue! There are many templates out there you can literally copy and paste - find one that fits your voice and context if this temple doesn't feel quite right.