For those of you that have visited Thailand and or seen these cotton wrist bands and wondered .. what's this about 

They have significant meaning, but with popularity comes commercial opportunity.

The significance of the bracelets is to understand the importance of their blessing

from a monk the culture is generally to wish good luck or health a chant or blessing during the binding of the braclet onto the persons wrist.

or village elder who may give a wrist band to
a returning member of the village to summon or call back your "Kwan" which may have gone wondering during hyour travels ... Kwan is your centre of spirit  read more about "kwan" here
or to a visitor to ensure their Kwan is balanced during their visit

or from one family member to another or to a friend to wish them happiness or friendship and goodluck etc.,

or simply offered by someone to another to recognise their good deed ie., to be a visual reminder for good karma

otherwise they are commonly found by street vendors sold as a fashion accessory.