Should you edit in 8bit or 16bit... or 32bit?? As always, it depends on your images, your equipment, and your intended usage.
What is 8bit
Lets start with the basics of explaining what a "bit" is when talking colour, it describes in what state a colour is in. Think of it as "yes or no", or in colour, quite literally "black" or "white" in the case of 1bit colour. Each extra "bit" doubles the available information.
In the above graphic - in 1 bit, there are 2 options
2bit - 4
3bit - 8
4bit - 16
up to in this case, 8bit - 256 possible colours.
Now what "8bit" means in the case of RGB images, is 8bits per channel, or "24bit colour", as such there is 256 possibilities for Red, Green and Blue that make up our images, which when multiplied together make up to the often heard "16.7 million colours".
Going up to 10bit, you get 1024 per channel, "1.07 billion colours".
Going to to 16bit, you get 65536 colours per channel, "280 trillion colours... or a lot".
The vast majority of screens around the world can only display 8bit colour, with 10bit becoming popular in recent years on high end computer displays and even some TVs. However to utilise this feature requires specific computer setups and media designed for the larger bit depth (known as Deep Colour) to output in 10bit, so to utilise it fully, make sure you do your research on if its its possible with your setup.
So what should you use?
In my opinion, while you are actively editing an image, 16bit is perfectly acceptable and often beneficial when manipulating smooth colour gradients. The best examples are the sky, especially at sunrise/sunset, or especially when working on your image in black and white as you no longer have 16.7 million colour available to you and are now down to just 256 colours in 8bit. Using 16bit would bring your range from black to white up to 65536 possibilities, a far more useful gradation.
Another reason to use 16bit over 8bit is when your workflow utilises a wide colour gamut such as AdobeRGB or ProPhoto, the increase in values allows for finer control of colours. Click here to learn more about Colour Spaces and why ProPhoto isn't such a great idea.
Going up to 32bit in Photoshop provides no "real world" benefits in photo editing even though you now have 4294967296 colours per channel. Your monitor cannot display it, your camera likely could not capture anything remotely close to it and the increase in file size will likely slow down your workflow by having unnecessarily large files.
Once your image is finalised however and is being uploaded to the web, or sent to your lab for printing, 16bit no longer has any benefit, and is simply doubling the file size. All files you output will not be adversely affected by using 8bit.
Using 8bit from the start is the most compatible for all devices and screens and unless your image requires the higher bit depth of 16bit, your computer and storage devices will thank you for the reduced file sizes.
Here at Art House, we prefer to receive files in 8bit as it keeps transfer times down and saves significantly on file storage.