what is strcat in c code example

Example: string strcat function in c

#include <stdio.h>
#include <string.h>

int main() {
   char str1[100] = "This is ", str2[] = "A Name";

   // concatenates str1 and str2
   // the resultant string is stored in str1.
   strcat(str1, str2);

   puts(str1);
   puts(str2);

   return 0;
}