Well, in 1860, Sweden decided they were going to have the ministers begin copying birth, marriage, and death information from the parish registers onto more condensed forms that would then be sent to the Statistiska Centralbyrån (Central Bureau of Statistics) in Stockholm. These were collected by län (county), and called utdrag ur födelse- vigsel- och dödböcker (extracts from birth, marriage, and death books).
Because the information from the parish registers was condensed, the information did not always match what was copied into the extracts. Many times, the extracts did not include information that would normally be found in parish records, such as witnesses at christenings that may have been helpful in solving genealogical problems. Other times, the extracts included additional information that would not have been found in the parish registers. You still get the important information, though, such as the name of the person/persons born, married, or buried, name of the parents and their marriage date, (depending on the event), the specific farm they were living on (which is important for clerical surveys), and ages of people involved (also depending on the event).
As mentioned above, these extracted records were kept according to län (county), so when you need to find them you will usually need to look on the county level in most repositories which house copies of these records. In the Family History Library, for example, you will want to look under the county, and then choose the "civil registration" heading to find the extracts.
Another thing you should know about these extracts, is that the books they were recorded in only included one year's worth of records because they were required to be sent annually. The purpose of doing so was so the government could easily determine yearly statistics for the country based on the church books, since that was where basically everyone had their events recorded. Because of the yearly basis of the volumes, you will most likely need more than one microfilm when you are trying to search a span of years, as each roll will most likely only cover one year in the county.
The next time you hit an end in your Swedish parish records, you will no longer have a mystery on your hands. You will know you need to look in civil registration records for the information you need.