Question about Render Area

[Sanchezman]

Many NES emulators have the option of (or force) the removal of the left and rightmost 8 pixels of the screen. Why is this? Does the NES not normaly render this area? Am I wrong to design a game that uses those left and rightmost 8 pixels?

[Shiru]

Old TV sets weren't guaranteed to display full raster, so the leftmost and rightmost columns could not be visible there, as well as few top and bottom rows. You can use them, just don't put anything important for gameplay there, like health bars.

[tepples]

Further info about overscan is available on Wikipedia and NESdev Wiki.

tl;dr: Avoid the left 8, right 8, top 16, and bottom 11 pixels for important indicators.

[rainwarrior]

A lot of CRTs even if they're actually displaying those pixels on the screen might have wood or plastic over that part of the screen, too.

[qbradq]

Emulators have this option to hide attribute glitches on games like SMB3. It's a reasonable way to check your screen-safe area handling though.