Is It Useful to Have Multiple Partitions?

Good evening to all,

I wanted to know if it was useful to have 2 partitions on the pc, lets take my case I have 2 partitions if I Delete and Merge Them , Then what Will Happen ? Also Tell the Softwares useful in creating and deleting partition thank you in advance

Mutliple partitions will not help any more than one huge drive. Multiple partitions are only beneficial when you are running more than one OS on your system. For example, I am running Win XP Pro and Windows Server 2003. I have also had WinME, Win2K Pro and Win 2000 Advanced Server on one machine in three partitions, all running fine. Personally, I wonder how big is your hard drive and how long has it been since you last ran defrag after you have removed all the internet junk form your Windows system? The comment about Windows rearranging and reallocating 'stuff' to fit it's own needs is an unusual comment with Windows. What kind of programs you are running. I am an MCP for Win XP Pro and have learned that letting Windows set the size of your virtual memory is the best, unless you are doing something really unusual with your system. If you run low on virtual memory and if there is enough free space on your hard drive, Windows will automatically allocate more.

The isolation of the operating system files into multiple filesystems is a protective measure.

The idea is to let something like the root ("/") filesystem fill to capacity (because you mis-spelled '/dev/rmt/om' [note the letter, not the number]), while retaining space in other mountpoints like '/tmp' and '/var' for the operating system to continue to work.

Partitioning allows the creation of separate areas for what are commonly known as scratch disks that are used by some programs as a temporary work area. Adobe Photoshop and many other graphics and multimedia editing programs that work with very large files experience a substantial performance benefit from having a separate, defined scratch partition.
Partitioning allows one system to contain multiple operating systems on separate partitions. Depending on what operating systems are involved in the multi-boot scheme it can impact the file system that must be used, but the capability is available.
Partitioning increases system stability. Breaking a hard drive down into smaller parts makes sense to me. Toss 100 - 200 gigabytes of operating system, applications, data, music, and other miscellaneous items onto one large partition and you're asking for trouble. Something is bound to go wrong with something and it's much easier to diagnose a problem when the drive contents are separated into smaller chunks.