I'm preparing for the IZ0-031 exam. Here's one explanation I need to understand. A locally managed tablespace is created as follows

" DATAFILE '/u02/oracle/data/my_local01.dbf' SIZE 50M

The explanation to this on a particular website was as follows

"Notice the EXTENT MANAGEMENT clause in the statement – this informs Oracle that you will locally manage the tablespace. It also informs Oracle that the extents will be auto-allocated in compliance with Oracle’s internal scheme. Initially the extent size is 64 Kilobyte. Oracle automatically sets the following extents. When the total allocated space reaches 1 Megabyte, Oracle increases the extent size 1 MB and then to 16 MB, and finally to 64 MB "

Ok so its the 1mb,16mb,64mb part that i dont follow and the relation it has to the datafiles. I'd be glad if someone could help me feed it into my head.