Now a days, most computers include hard drives with 100s of gigabytes of space. In such a scenario, it is inevitable that you partition the hard drive to optimize the use of space. Dividing your hard drive into individual partitions for your operating system, programs, data files, music, and images provides better organization and, most important, much better data safety in the event of a drive crash.
This article explains why it is prudent to partition your hard drive to more manageable chunks.
On the other hand, if you already have a well partitioned hard disk and you wish to combine two or more chunks of disk partitions to save your data, instead of deleting a partition, you can always use logical volumes which form a layer above the physical partitions and which can span multiple partitions. Read more about how you can create logical volumes and resize them in Linux. The article - how to manage disk space with LVM also makes an interesting read.