(1) Sin, or bad Karm (actions). All these Karm hurt others, many times even ourselves.
(2) A-Dhaarmic Karm - not prescribed by Shaastra. Manu says that sin occurs by not performing actions recommended by Shaastra, by performing actions prohibited by Shaastra, and by having no rule or control
over actions of sound, touch, form, taste and smell. Thus sin occurs as three types. The man who does sin should definitely do redemptive acts.

What happens if somebody doesn't do Praayashchit (redemption) for his sins?
Yaagyavalkya Jee says - If the people who commit sin and do not do Praayashchit and do not even feel the guilt of having performed the sin, they suffer very hard and cruel punishments in hell. There are 26 types of hell. They are Tamisra, Lauha-shanku, Mahaaniraaya, Samali, Raurav, Kumbhal, Poothimruthika, Kaalasootrathapan, Mahaanarak, Kaakol, Sanjeevan, Mahaapada, Aaveesee, Andha-tamisra, Kumbheepaak , Asipatravan, and Tapan. These are the hells which would be attained by people who do Mahaa-paatak (greatly sinful acts) and Upa-Paatak (subsidiary sinful acts) and who do not perform redemption for them.

Yagyavalkya Jee further says - "The people who do the five Mahaapatakas would suffer in cruel hells for a long time and take several births in this world....  If we do holy or sinful acts, first you would undergo blessings and punishments in the present birth and would go to heaven or hell. If you do it intensively you would see the results in three years, three months, and three days only.

Manu has also talked about the the type of rebirths taken by people who commit different types of sins

Types of Paap
There are 10 types of Paap under three categories - 
3 Physical Paap - taking somebody's thing without his giving; Hinsaa (killing somebody); and illicit relations with other woman; 
4 Vaachik (speech related) Paap - harsh speech; lying or telling bad about somebody else'; illogical talk; and 
3 Mental Paap - thinking about taking other's wealth, thinking to harm others, and fearing with death.
(Naarad Puraan, p 651)

Paap are of five types - 
(1) Aardra - sin committed by will
(2) Shushk - sin committed unwillingly
(3) Laghu and Sthool - small and big
(4) Physical, mental or speech related
(5) Sin committed unknowingly
(Padm Puraan, 5-Uttar, p 785)

The five great sins are -
(1) Brahm Hatyaa or Stree Hatyaa - Killing of a Braahman or woman
(2) Suraa Paan - Drinking of wine (except in certain conditions prescribed by Dharm)
(3) Stealing of gold
(4) Cohabiting with the wife of Guru or person regarded as Guru (uncle etc), and
(5) Cheaters
[Bhaagvat Puraan, Greatness of Bhaagvat, 4th Chapter)

Shyaamaa Rahasya Tantra says that the five Ma-Kaar are the sources of great sins, such as, Matsya (fish), Madiraa (liquor), destroy all great sins - Mahaa Paatak Naashan.

Nine types of sins - Anger, passion and avarice are the three enemies of men. The one who is subject to these commits the nine types of sins.
(1) Mahaa-Paatak - Greatest sins - Manu says killing of Braahman, drinking, stealing of the gold of Braahman, raping teachers wife and being friends with these four types of people are Mahaa-Paatakee.
(2) Adhi-Paatak - Great sins - Yam Raj says that the man who rapes his Mother's sister, friend of mother, daughter, father's sister, uncle's wife, sister and mother in law is Adhi-Paatakee. Yaagyavalkya Jee says that having sex with a debased one, aborting a fetus and killing husband are Adhi-Paatakee for women.
(3) Sama-Paatak - Ordinary sins - Yaagyavalkya Jee says that insulting elders, insulting Ved, troubling friends and forgetting the already learned Ved are sins equivalent to Brahm Hatyaa. Drinking Coconut water in a bell metal vessel, drinking milk mixed with salt, taking bath in water used by a washer man and drinking milk or curd in a copper vessel are considered equivalent to drinking Alcohol. Manu says that Stealing the article given to us for safe custody and stealing land, diamond and jewels are equivalent to stealing gold. He who does evil things without intention or motive with his daughter, Dalit woman and the wives of friends as well as son, he commits sin equivalent to raping the teacher's wife. These are classified as Sama-Paatak. But if he does it willfully it is Adhi-Paatak.
(4) Upa-Paatak - Subsidiary sins - Manu says that conducting Yag on behalf of a man who does not know Ved, deserting teacher, father and mother, forsaking fire and Ved, giving up sons, the elder brother remaining bachelor when the younger one is married (thus the elder commits Pariviti sin and the younger Parivedan), giving away girls to such brothers, performing marriages of such brothers, raping of a virgin, living out of interest earned from money, serving a Brahmchaaree, selling water tank, flower garden, wife and son, not performing rituals like sacred thread ceremony at the proper time, not obeying paternal and maternal uncles, teaching Ved and Vedaant for money compensation, reciting Ved and Vedaant for money, Selling goods like Gingelly, being in charge of the treasury of the king, running machines, pinching medicinal plants, earning a living by use of women, performing worship for spoiling others, attracting people by magical chants, Mool Karm (?), cutting living trees for sake of fire wood, cooking for our own eating, eating food in homes of people who abuse Shaastra, being a government servant , Not doing Agnihotra (mandatory fire worship), stealing metals other than gold, not returning loan, reading the science developed by Mlechh, engaging in music and dance, stealing grains, copper and similar metals and cows, drinking habit, sex with wives of others, and troubling Kshatriya, Vaishya and others are called Upa-Paatakee.
(5) Sankaree-karan - Getting polluted - Manu says that killing of donkey, dog, camel, deer, elephant, goat, sheep, fish, snake and buffalo are Sankaree-karan sins.
(6) Malinee-karan - Making dirty - Troubling worms, insects and birds, eating food mixed with alcohol and
stealing flowers, firewood and fruits are classified as Malinee-karan sins.
(7) Apaatri-karan - Dealing with undesirables - Taking money from those who do not follow rituals, selling things, serving others and telling lies for everything are Apaatri-karan sins.
(8) Jaati Bhransh-karan - Destroying community - Wounding, troubling Braahman and making them sad, smelling things like onion, garlic etc and denying sex to the husband are Jaati Bhransh-karan sins.
(9) Gyaan Agyaan Krit Paap Vichaar - Sins done knowingly and unknowingly - Redemption is only for those sins which are committed unknowingly. For sins committed knowingly, there is no redemption.

In Mahaanirvaan Tantra (p 264) Shiv says to Paarvatee - "Know that there are two kinds of sin - that which contributes merely to the injury of one's own self, and that which causes injury to others. Man is released of the sin of injuring others by the punishment inflicted by the King and from other sins by expiatory rites and Samaadhi. Those sinful men who are not purified by either punishment or expiation cannot but go to Hell and are despised both in this world and the next."