Okay, so what is a sin anyway?

God gave us free will, the ability to reason, and a sense of moral responsibility, all with the intent that we would use these gifts to live by His law.  When we use these gifts to deviate from Gods law it's called sinning.

Original sin occurred when Adam gave into temptation and ate from the tree of knowledge.  The consequence of this is that all humans are born with an innate desire to sin, making it so that a conscious effort must be made to live by God's law and to receive God's grace.

Personal sins are all the sins that we make by our own personal lives.  There are two types of personal sins:

1. Venial: These usually involve sins that are not of grave matter.  They may also include sins you do not know you are committing, or sins you do not deliberately intend to commit. These sins do not cut you off from the Grace of God as such sins do not mean a person has rejected God.  They may be forgiven by the Sacraments of Eucharist and Reconciliation (Acts of God's Grace). 
2. Mortal: Sins that are merit damnation without reconciliation. These are sins involving a grave or serious matter, either by intentionally doing something severely wrong or by intentionally omitting something from one's life. Such sins cut the sinner off from God's grace. It's the rejection of God (spiritual death) that results in eternal punishment in Hell.  

Tempting each of us are what are often referred to as the seven deadly sins (also referred to as capital devices or cardinal sins), each of which is associated with one of the seven holy virtues, and each of which may be associated with a venial or a mortal sin.

1.  Pride (Vanity, Superbia): An unrestrained or improper appreciation of your own worth.  It's excessive belief in your own abilities to the point that it interferes with your recognition of the grace of God. It is the sin from which all other sins arise.
Sev
2.  Envy (invidia): The desire to own that of which (traits, status, abilities, situation, materials) is not yours.

3.  Gluttony (Gula): Consuming more than what is required.

4.  Lust (extravagance, luxuria):  Inordinate craving for the desires of the body

5.  Anger (Wrath, ira):  Spurning love in favor of fury.

6.  Greed (Avarice, Covetousness, avartia):  Desire for material wealth or gain at the expense of spiritual wealth or gain.

7.  Sloth (acedia):  Avoidance of physical or spiritual work.