I'll expand a bit on my previous post.
There are four stages:
1) Servant of God
The Congregation for the Causes of Saints investigates the person's life. The person is called Servant of God through this process.
After a time, the Congregation may decide to recommend to the pope that he proclaim the Servant of God's heroic virtue, at which point he becomes
A Venerable is someone who the pope has proclaimed to have lived a life of heroic virtue.
At this point, upon the establishment of one miracle (not needed for martyrs), the Venerable can be beatified, and is now called
. This is the recognition by the Congregation for the Causes of Saints that the person has gone to heaven and can be asked for intercession. He or she is given a local feast day that is not universal---the Church gives permission for local public veneration, not Church-wide.
Beatification is not considered infallible. It can be considered along the lines of a private revelation.
After the establishment of another miracle, the Blessed can become a
He or she is now universally venerated and whose feast day is Church-wide. This is infallible.
Of course, the process is much more complex than the bare bones I've described, and it takes decades, even centuries in some cases.
Here is a summary that goes into some more detail:http://www.ewtn.com/johnpaul2/cause/process.asp