Jains, like Hindus and Buddhists, believe in the cycle of reincarnation and that the way to escape that cycle is through attaining enlightenment. The soul is held in the cycle by all the trappings of life: strong emotions and attachments to other people or things, actions that cause harm, participation in the animal acts of living. A follower of the Jain religion can choose to aim for enlightenment, and pursue the life of a monk, attempting to divest themself of all that karma trapping their soul here in this plane of existence.
To the western way of thinking, saturated in the ideals of the Abrahamic religions, some Jain beliefs are radical and strange. To me, the two biggest differences were that a Jain is in no particular rush to achieve enlightenment; and that to a Jain, intent and action are separate. Let me explain:
Jains believe in reincarnation. Now, if you genuinely believe in reincarnation, you don't have to achieve enlightenment during this life. There is no reason not to enjoy the life you are living right now. I mean, yes, it's best if you don't attract a whole lot of extra karma by causing unnecessary harm, so most Jains will practise veganism or even fruitarianism, and will avoid jobs that might cause harm to living creatures. But there is no shame in electing not to try for enlightenment this time around.
Jains try to avoid harm to all living creatures. A Jain monk will not consume any food that involves harming animals, or even plants. Foods that kill the plant when they are harvested are considered to attract karma, and are avoided. Carrots, for example. By pulling up the carrot you kill that carrot plant. A plum would be fine, because the plum tree lives on year after year.
Jain monks also avoid harming even the smallest and simplest living creatures. Jain monks own very few possessions: a bowl for food, and a small broom to sweep the ground in front of them, to ensure they don't step on any insects, even tiny ones. The 'sky-clad' monks don't even wear any clothing (although in my view their insistence that they own a penis probably attracts bucketloads of karma. Misogyny is a real downer. The 'white-clad' monks might own a loin cloth or robe but at least they have managed to get past any karma-attracting attachment to their genitals). In centuries past Jains were regarded as a bit crazy because one of their whacky beliefs was that there were tiny, microscopic life forms that you couldn't even see with the naked eye (or naked monk) and to achieve enlightenment one ought to avoid harming even these tiny creatures.
Furthermore, a Jain monk is only aiming for their own enlightenment by avoiding karma on their own behalf. Having been raised at least nominally Catholic, I was accustomed to the concept that one's thoughts matter almost as much as one's actions: doing the right thing for the wrong reasons will not fool God, and won't count half so much as pure intent. The Jains have no such compunction. Among other things a Jain monk is supposed to be on the move, spending no more than three days in any one location lest they start to form an attachment. The Jain monk will generally refuse to travel in a vehicle like a car, because the risk of injuring living creatures.
But in the Jain worldview, there's nothing to stop one's devoted followers (ordinary Jains who might be spending a few days or weeks improving their chances for the next round of reincarnation) from driving on ahead with a truck full of supplies, setting up a tent and cooking a fruitarian meal ready for the tired monk to enjoy at the end of a hard day sweeping the ground and begging for alms. That isn't the monk attracting karma: it's the follower who has chosen to ride in the vehicle and own the tent and so on.
This 'not my karma' view also coloured the Jains' interactions with other cultures over the centuries. In pursuing careers that avoid harm to animals, many Jains ended up as merchants, jewellers and bankers. This meant they were comparatively wealthy, and occupied a place in Indian society somewhat akin to that of the Jews in medieval Europe: a relatively wealthy but despised minority. In some areas Jains paid off Mughal invaders to ensure the safety of their businesses and monuments, leaving the Hindu majority to bear the brunt of the invasions. There are places in India where the oldest and grandest monuments are Jain, for this reason.
It's a long time since I noded my homework, but I found some notes from a lecture I attended at the ANU in 2001, and I thought I might share them.
The young man giving the lecture had recently returned from several months spent living with the 'white-clad' monks and was engaged in writing his doctoral thesis on the Jains. I neglected to record his name, or the date of the lecture, but according to my notes my fingers were feezing, some guy called Nathan gave me his phone number, and the concept of an atheist religion turned my world upside down.