Types of chain?

What's the difference between the different types of chain, like x-ring or o-ring. I probably have the names slightly wrong too.

[PyroUK]

Shiny ness.

And possibly longevity but I thought it was mainly shiny ness

[timwilky]

All to do with the seal profile |X| vs |O|

so X ring have two points of contact whereas O ring only have a single point of contact.

Supposedly, X have less resistance to movement in the link and therefore make the chain slightly more efficient.

There are 3 types, maybe more
Standard, basic chain without any rubber seal between the links
O ring has plain O rings between the links
X ring has slightly fancier O rings between the links

The O and X ring require less mainenance, pay your money take your choice. Go for an established brand and look after it and you will be fine.

[Sid Squid]

Broadly speaking there are two types of chain; unsealed and sealed. Unsealed is just that, no seals of any kind whatever the shape, just the same as you would find on a bicycle. Sealed chains are the ones referred to as 'O' or 'X' ring, the two differing in the shape of the seal, an 'X' ring chain has four smaller points of seal contact, an 'O' ring two larger ones, in theory an 'X' ring should perform better, in reality you'd be hard pressed to tell the difference and the exact grade of chain would make the difference in performance and wear rate.
The seals in question can be seen between the inner and outer sideplates, and hold in place the grease that is used in the manufacture of the chain in the joint articulations, and exclude grit and dirt meaning that the lubrication of the said parts is improved, leading to reduced wear and longer life. Of course you don't get anything for nothing and the seals ever-so-slightly increase the resistance of the chain links movement, which absorbs a teeny fraction of your engine's power, for this reason some racing chains are not sealed - but of course wear is not a great consideration in that application.

Makes sense. Thanks Sid, and everybody else.