Before sealing the fermenter, some measurements need to be taken. This is done by first taking a sample of the wort from the fermenter with a sanitized sampling device. A ladle will work fine if it has been sanitized and rinsed with clean water.
The sample is then poured into the cylinder that comes included with the hydrometer and the hydrometer is inserted into the wort sample. Then the specific gravity is read.
Since temperature affects specific gravity, the temperature of the sample is also read. These two readings can be used later in the Finished Beer Analysis featured at this site.
The readings are recorded as the original gravity and original temperature readings. Notes should be made about times and procedures followed during the entire brewing session, so that in the future the process can be duplicated. You never know if this brew will be one you want to repeat.