Where Is TOC Located on a CD

Every CD (Compact Disc) has a TOC (Table Of Contents) section located in the "lead-in" area on the CD. For an CD-DA, (audio CD), the "lead-in" area is located between radius 23mm and 25mm,
The illustration also shows other interesting areas on a CD:

Radius 22-23mm: Inner buffer zone. 
Radius 23-25mm: Lead-in area. 
Radius 25-58mm: Program area. 
Radius 58-58.5mm: Lead-out area. 
Radius 58.5-59mm: Outer buffer zone. 
Radius 59-60mm: Rim area.

The size of the "lead-in" area is about, 4,500 sectors with a capacity of about 9 MB.
The TOC in the "lead-in" area contains the total length of the recording session, a list of tracks and their starting addresses and some other information.
Note that on a multi-session CD, each session will have its own "lead-in" area and TOC.
On a recordable/writable CD (CD-R), there is an extra area called PMA (Program Memory Area) before the "lead-in" area. The PMA is located between radius 22.35mm and radius 23m.
The PMA is used by the recording process to store a temporary copy TOC, before the session is closed. After the session is closed, the TOC is written to the "lead-in" area.