The following is by Dennis Shea (NCAR):

Text files encountered in climate research are typically structured as a sequence of lines terminated with a special 'end-of-line' character (typically, the "null" character). Most climate oriented text files are in ASCII format. An advantage of text files is that they are human readable. Unfortunately, text files are very inefficient for archival or transmission of data. As a simple example, consider  x=-123.456. In floating point binary form, this is stored as four bytes (32 bits) while in ASCII/text format, this takes eight bytes (64 bits) because each ASCII character requires eight bits.

Most software tools have functions which can automatically read data organized into rows (lines) and columns.