Blocks??

hi
Can anyone tell me in the view dba_free_space what does the column BLOCK is for ...consider the following query below...
SELECT BLOCK_ID, BYTES, BLOCKS
FROM DBA_FREE_SPACE
WHERE TABLESPACE_NAME = 'TABSP_4'
ORDER BY BLOCK_ID;

BLOCK_ID BYTES BLOCKS
---------- ---------- ----------
2 16384 2
4 16384 2
6 81920 10
16 16384 2
27 16384 2
29 16384 2
31 16384 2
33 16384 2
35 16384 2
37 16384 2
39 8192 1
40 8192 1
41 196608 24
13 rows selected.
Now what i wanna know if the BLOCKS columns shows no of blocks then shoudn't each block shd have seperate block_id .......