This example is taken from figure 10.5 in the textbook. It demonstrates how we can use *, ?, and [ ] as wildcard characters to match multiple files. The use of these characters can be complicated because they are the same characters as used in regular expressions. But in the case of wildcards, the * and ? have different meanings from the metacharacters in regular expressions. The use of wildcards, also called filename expansion or globbing, allows you to specify multiple files in such Linux commands as ls, cp, mv, rm, etc as in ls *.txt.