I used them to learn for "Data compression". Solutions can be found as HTML comments.
BTW: try to refresh this page…
0 1 0 1 0 1 0 0 1 0 0 0 0 0 1 0 1 0 0 1
0 0 0 0 0 0 0 1 0 0 1
0 1 0 1 0 1 0 1 1 0 1 0 0 0 0 0 0 0 0 1
0 0 0 1 1 1 0
0 0 0 0 1 1 1 1 0
0 0 0 0 0 1 1 0 0 1 0 0 1 1
0 1 0 0 1 0 1 1 1 1 0 0 0 1 1 0 1 0 0
0 1 0 0 1 0 0 0 0 1
0 0 0 0 1 0 0 0
1 0 1 0 0 1 0 0 1 0 0 1 0 1 0 1 1 0 1 0 1 0 0
1 0 1 0 1 1 0 1 1 0 0 0
1 0 1 0 1 1 0 0 0 1 1 0 1 0 1 0 0 1 0 0 0 1 0
1 0 0 1 0 1 1 0 0
1 0 0 1 1 1 0 0 0
1 0 0 1 1 1 0 1 0