There are great TV shows where everything is surface-level and that's just fine - what you see is what you get.
But truly iconic series will often dare to take things further and reveal just how much obsessive thought has gone into even the most apparently mundane of details.
The beauty of online discussion, of course, is that fans can put their seemingly supernatural observational abilities to good use by uncovering big secrets that were plastered in front of the viewer's face in a brilliantly subtle way.
Whether you realise it for yourself or learn the truth from the fine folks over at /r/TVDetails, appreciating how much effort has been put into rewarding attentive viewers can make watching a TV show so much more satisfying.
With each of these 10 hit shows, they cleverly concealed a major plot development or character beat in the last place anyone would think to look - in plain sight, of course.
You've seen it and you've taken it in, but you haven't clocked its grander meaning until years later, if at all (until someone else pointed it out, at least).
But thanks to the beauty of subreddits and other social media avenues, these bombshells are now out there for everyone to savour, from insane foreshadowing to low-key incredible character development.
These shows won't ever quite be the same on repeat viewings, and all the better...