In this article, we'll examine this simple method as we take a very small file through the basic process of compression. Most types of computer files are fairly redundant -- they have the same information listed over and over again. File-compression programs simply get rid of the redundancy. Instead of listing a piece of information over and over again, a file-compression program lists that information once and then refers back to it whenever it appears in the original program. As an example, let's look at a type of information we're all familiar with: words.
If you are healthy person who has been exercising regularly, after you donated blood, you wonder whether you can exercise right after that. The answer is no. You should only exercise after at least 5 hours of resting. Do not run, swim, do weight training or other rough movements during the first 5 hours of donation. In fact, even after that period, your competitive performance in the court or track may be affected.
You will have some time to relax while the bag is filling. (For a whole blood donation, it is about 8-10 minutes. If you are donating platelets, red cells or plasma by apheresis the collection can take up to 2 hours.)