The time taken a particular record within a file depends upon how the file is organised. For example, imagine a file containing information on a large number of people, i record per person. The simplest type of file is a sequential (or serial ) file, in which the records are simply organised in the order in which they were added to the file. To find any particular person you word need to read each record starting at the beginning of the file until you found the person you wanted. Each search would require you to read an average (n+1)/2 records (where n is the number of records).