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What is file compression?

File compression is a process of "packaging" a file (or files) to use less disk space. Compression works by minimizing redundancy in a file's code. Compression software allows you to take many files and compress them into one file, which is smaller than the combined size of the originals.

Why do I need it?

• To make file storage and file backup more efficient.
  File compression allows you to store and back up significantly more data, faster.

• To effectively post files on a Web page for someone else to download or to send large documents as email attachments.
  Files can become corrupted when they are transferred over the Internet in an uncompressed format. Transfer time is lessened when files are compressed. File compression is often a necessity for sending large documents over the Internet as email attachments since most email systems limit the size of each email message. Often it is easier to compress multiple documents into one document to attach to an email message rather than attaching them one-by-one.

• To download and open files from a Web page or from your email application that have been compressed .

What are the drawbacks?

Compressed files must be uncompressed to be opened. When using file compression to send email attachments, the recipient of the message must understand how the file was compressed and have the tools to uncompress the file.

Do I have compression software?

Macintosh OS X computers have a built in file compression system that will archive files as zip files.

Windows XP computers distributed through the Boston College computer replacement program (BCCR) have WinZip software. WinZip archives files as zip files.

Windows Vista computers have a built in file compression system that will archive files as zip files.

How do I compress/uncompress a file(s)?

WinZip for Windows Instructions

Windows Vista Compression Tool

Macintosh OS X Archiving Tool Instructions

Email Attachment Compression

Boston College limits the size of email messages to 15M. This includes both the attachment and the text of the email message. Please be aware that the recipient of your message may have a lower limit. If you need to send a large document, you will need to compress the files first so that their size is within the limit.