GEOM is the main storage framework for the FreeBSD operating system. It is available in FreeBSD 5.0 and higher and provides a standardized way to access storage layers. GEOM is modular and allows for geom modules to connect to the framework.

Wikipedia: GEOM
FreeBSD Handbook: GEOM: Modular Disk Transformation Framework

# fdisk /dev/da1
******* Working on device /dev/da1 *******
parameters extracted from in-core disklabel are:
cylinders=3892 heads=255 sectors/track=63 (16065 blks/cyl)

Figures below won't work with BIOS for partitions not in cyl 1
parameters to be used for BIOS calculations are:
cylinders=3892 heads=255 sectors/track=63 (16065 blks/cyl)

Media sector size is 512
Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 1 is:
sysid 12 (0x0c),(DOS or Windows 95 with 32 bit FAT (LBA))
    start 32, size 62530592 (30532 Meg), flag 80 (active)
        beg: cyl 0/ head 0/ sector 33;
        end: cyl 1023/ head 254/ sector 63
The data for partition 2 is:
<UNUSED>
The data for partition 3 is:
<UNUSED>
The data for partition 4 is:
<UNUSED>

# gpart show
=>      34  29323661  ada0  GPT  (14G)
        34       128     1  freebsd-boot  (64K)
       162  27262848     2  freebsd-ufs  (13G)
  27263010   1466368     3  freebsd-swap  (716M)
  28729378    594317        - free -  (290M)

=>       1  62533295  da1  MBR  (30G)
         1        31       - free -  (16K)
        32  62530592    1  !12  [active]  (30G)
  62530624      2672       - free -  (1.3M)

=>       1  62533295  diskid/DISK-AA010922140523382836  MBR  (30G)
         1        31                                    - free -  (16K)
        32  62530592                                 1  !12  [active]  (30G)
  62530624      2672                                    - free -  (1.3M)