Custom Options in Magento Product

Custom Options are way to offer selection of product varriation it's not rely on attributes.

it have limitations that you are unable to track
inventry based on any varriation, and custom options is not used in grouped,configurable or bundle product.
 Custom Product Option is different form attributes we can use it in simple product for adding like sizes, colors etc..

Steps to adding custom options

1. On the Admin menu, select Catalog > Manage Products. 2. In the list, open the product record in edit mode. 3. In the panel on the left, select Custom Options. 4. In the upper-right corner, click the Add New Option button. Then, do the following: a.  In the Title field, enter a name for the property. b. Set the Input Type you want to use for data entry. c. Set Is Required to “Yes” if the option must be selected before the product can     be purchased. d. In the Sort Order field, enter a number to indicate the order of this item in the list of options. Enter the number 1 to display this option first.

5.

Click the Add New Row button a. In the Title field, enter a name for this option. b. In the Price field, enter any markup or markdown from the base product price that applies to this option. c. Set Price Type to one of the following: Fixed The price of the variation differs from the price of the base product by a fixed monetary amount, such as $1. Percentage The price of the variation differs from the price of the base product by a percentage, such as 10%. d. Enter a SKU for the option. The option SKU is a suffix to the product SKU. e. In the Sort Order field, enter a number to indicate the order of this item in the list of options. Enter the number 1 to display this option first. 6. When complete, click the Save button.