Beginner question about making a beep sound

I am so sorry to ask such a simple question, which i have been thinking for whole night already.

Here are the codes

module music(clk, speaker);

input clk;

output speaker;

reg [15:0] counter;

always @(posedge clk) counter <= counter+1;

assign speaker = counter[15];

endmodule

[/B][/B][/B][/B][/B][/B][/B][/B]My question is :

1. Anyone can explain the logic to me. I very a beginner.

2. " always@(posedge clk) counter <= counter+1;" means it has positive clock only when counter is smaller than counter +1, but what is counter physically in this case??

3. Assign speaker to one of the value of counter is understandable, however, why then the speak will make a sound of frequency 381Hz if the input clock is set to be 25MHz, i know it's from 25MHz/65536= 381Hz, but i just dont understand why. how come? what is happening here?

Anyone can explain this? i will appreciate that. Thank you so much:oops: