Regional codes are entirely optional for the maker of a disc. Discs without region locks will play on any player in any country. It's not an encryption system, it's just one byte of information on the disc that the player checks. Region codes are a permanent part of the disc, they won't "unlock" after a period of time. 

There are 8 regions. Players and discs are often identified by the region number superimposed on a world globe. If a disc plays in more than one region it will have more than one number on the globe.

So, if you have a region 1 player you will only be able to play code 1 or 0 DVDs.
 

Code	Region
1	U.S., Canada, U.S. Territories
2	Japan, Europe, South Africa, and Middle East (including Egypt)
3	Southeast Asia and East Asia (including Hong Kong)
4	Australia, New Zealand, Pacific Islands, Central America, Mexico, South   America, and the Caribbean
5	Eastern Europe (Former Soviet Union), Indian subcontinent, Africa, North   Korea, and Mongolia
6	China
7	Reserved
8	Special international venues (airplanes, cruise ships, outer space.)
0	Region Free. Playable on any system.

NTSC & PAL
In addition to region codes, there are also differences in discs for NTSC and PAL TV systems 
The MPEG video on DVD is stored in digital format, but it's formatted for one of two mutually incompatible television systems: NTSC or PAL/SECAM. Therefore, there are two kinds of DVDs: NTSC DVDs and PAL DVDs. Some players only play NTSC discs, others play PAL and NTSC discs. 

All DVD players sold in PAL countries play both kinds of discs. These multi-standard players convert NTSC to PAL . 
Most NTSC players can't play PAL discs. A very small number of NTSC players (such as Apex and SMC) can convert PAL to NTSC. 

So, if you have an NTSC only DVD player you will NOT be able to play a PAL disc unless you use a standards converter box.