i have multiple items in inventory which needs to be categorized and i can see no options to categorize except from assigning item code on my items which is not what i need
Can you explain in more detail, perhaps using examples, what you are trying to achieve?
I am not sure what you mean by categorise? For what purpose? To use where?
i have multiple items like motherboards, processors, memory, hdd etc.
i have to categories them with the names ahead then i have motherboards of different companies and they also need to be categorised under these categories .
iso i want to categorize them in order to keep it handy for me to pick my item for sale invoice
As VacuumDog explained, you can use Custom Fields to hold this information but you will not be able to use the custom field to select the item when you create an invoice.
You can print the information on the invoice