Basic (De)Compression Parameters

Each archive type tends to have its own set of (de)compression parameters, some of which are supported only by the archive type in question. However, most archive types share a general set of (de)compression parameters, which are explained below.

Common compression/decompression parameters:
Parameter	Meaning
Priority	Determines how much time the operating system gives to the running task (compression/extraction). If you are compressing a large amount of files, which is a process that may take considerable time, you may set the priority low, and continue working with your computer while the compression continues in the background. Setting priorities higher than normal is not generally recommended as it will make your computer unresponsive, but may be required in some cases.
User Mode	Determines if the user is asked questions during an archive operation. For instance, while extracting files from an archive, the user may be asked if (s)he wishes to overwrite already existing files in the target folder. You may handle all questions yourself, or have the program decide internally which action is best. You may even log the results of an archive operation to a text file.

Common compression only parameters:
Parameter	Meaning
Compression Level	Determines how strong the compression should be. Stronger compression generally requires more time, but results in smaller archive files. It is recommended that you set the compression level as high as possible. Thus, the archives you create will be as small as possible.
Dictionary Size	Similar to the Compression Level parameter.
Solid Compression	When enabled, increases compression strength without requiring more compression time. However, decompressing files non-sequentially from a solidly compressed archive requires that all preceding files in the archive also be decompressed (to memory), thus slowing down the decompression process. It is recommended that you enable Solid Compression, despite the decompression time overhead, which is minimal.
Password	Protects archives with a password. You may use passwords during compression if you need to encrypt your archives. However keep in mind that experienced hackers may be able to easily crack some types of password protected archives.
Store Folders	Determines how files being archived are stored inside the archive during compression. There are generally three settings for storing folders: Do Not Store Folders: Files being archived are stored in the archive by their file name only. Store Relative Folder Information: Files being archived are stored in the archive by their file and folder names. The folder names are taken relative to the root folder of the compression operation. For instance, if you are archiving all files in a folder "c:\temp", files directly under "c:\temp" will be stored only with their file names, whereas files in subfolders of "c:\temp" will be stored by their subfolder and file names. Store Absolute Folder Information: Files being archived are stored in the archive by their full names, including full folder information. It is recommended you store relative folder information.
Recovery Information	Determines if archives created will contain recovery information. Damaged archives may be rescued successfully if they contain recovery information. This setting has some impact on the size of archives created. It is recommended you disable recovery information.
Span	Creates multiple archives of a given size. This parameter is useful if you wish to break up large archives into smaller, more portable pieces. For instance, you may wish to span archives onto floppy disks, or create multiple archives of a fixed size on your hard disk for easy uploading/downloading.

Common decompression only parameters:
Parameter	Meaning
Password	Allows extracting password protected files from a password protected archive. You will need to specify this parameter if you are trying to extract files from a password protected archive.
Extract into New Folders	Determines if archives are extracted to a subfolder, which bears the archive name, created automatically under the target extraction folder. This parameter may be useful if you are extracting multiple archives simultaneously, and do not wish to have their contents all mixed up.
Preserve Folder Names	Determines if files being extracted from the archive should be extracted using their stored path information in the archive, if any. It is recommended you enable this parameter.
Overwrite	Determines how already existing files in your target extraction folder are treated, if they share names with the files you are extracting from an archive. There are generally three overwrite settings: Always: Files already existing in the target extraction folder are always replaced with files being extracted from the archive. Ask: You will be prompted whether to replace a file already existing in the target extraction folder with the file being extracted from the archive. Never: Files already existing in the target extraction folder are never replaced with files being extracted from the archive.