.NET offers a lot of way to store a set of values like lists, queues, stacks, dictionaries, etc… each with their own (dis)advantages and performance characteristics.
Unfortunately I see a lot of developers just use the default List<T> without being conscious about this decision. Arthur Minduca created a simple flowchart to help you choose the correct structure for your specific situation:
Read the full article here: http://www.codeproject.com/Articles/1095822/Choosing-The-Right-Collection