What are ticks used for in PHP?

Answer 1

If by "ticks" you actually mean "back ticks", ie. the ` character, then they are the same as using the shell_exec() function. For example:

$foo = `ls`;

Would assign the output of the ls command to the variable $foo.

If on the other hand you're referring to the single quote, or apostrophe, then it is used as a string delimiter for strict text with no special characters. For example, the code:

$foo = 'bar';

echo 'test #1 says $foo\n';

echo "test #2 says $foo\n";

would output the following:

test #1 says $foo\ntest $2 says bar