Sexting arrived on the scene from the moment text messages came on to mobile devices, however even before then people used email to send naughty message to each other. Sexting exploded when people who had mobile phones sent naughty stories at first and then photos when cameras because the norm on mobile phones.
Sexting is legal in the UK as long as both parties consent and they are over the age of 18. (which is the legal age for sexual content in the UK), if you have not consented to sexualised material then this can be classed as sexual harrassment
The answer to that one is not easy, as not everything is for free, however local sex finder provides all members with a free login to go search the local talent, the women all go free 100% of the time.