Packers are tools that compress, obfuscate, encrypt or other methods to encode the original code. When the program runs it will decode the code into memory at run time. It is important that prior to starting the analysis assess whether the sample is packed, as it can alter the whole process. Analysis of packed executables is difficult because the code is encoded in such a way that makes it unreadable. Dynamic analysis of the packed program’s code is still possible, but the process is more complex, as you first have to identify the unpacking function location. This does not mean that only malware is packed, there is a legit reason for using packers, such as protecting the algorithms used in trading software. The reason the malware authors choose to pack the code is to avoid AV detection giving more time before it is detected.