There are three types of product relations in Magento: Up-sells, Related Products, and Cross-sell
Products. When viewing a product, Upsells for this product are items that your customers
would ideally buy instead of the product they’re viewing. They might be better quality,
produce a higher profit margin, be more popular, etc. These appear on the product info page.
Related products appear in the product info page as well, in the right column. Related products a
re meant to be purchased in addition to the item the customer is viewing. Finally, Cross-sell
items appear in the shopping cart. When a customer navigates to the shopping cart (this can
happen automatically after adding a product, or not), the cross-sells block displays a selection
of items marked as cross-sells to the items already in the cart. They’re a bit like impulse
buys - like magazines and candy at the cash registers in grocery stores.

Up-sells

To add Upsells to a product:

Log in to the Magento admin

Navigate to Catalog -> Manage Products

Find the product to which you want to add Up-sells

Select and edit this product

Select the Up-sells tab

From the products grid that appears, check any products you’d like to mark as Up-sells
(press “Reset Filter” to see all products)

Once a product has been checked, the “Position” field opens up. This determines the
sort order of the Upsells in the main product’s page

Press “Save”

You’re done! Navigate to the front-end and check out your newly created Upsells block!
(shown below)

In the above screenshot, you should assume your customers would rather buy a cup with
coffee in it, making it a perfect Upsell.

Related Products

To add related items to a product:

Log in to the Magento admin

Navigate to Catalog -> Manage Products

Find the product you want to add related items to

Select this product to load it for editing

Select the Related Products tab

From the products grid that appears, check any products you’d like to mark as related
(press “Reset Filter” to see all products)

Once a product has been checked, the “Position” field opens up. This determines the
sort order of the related products on the main product’s page

Press “Save”

You’re done! Navigate to the front-end and check out your newly created Related
products block! (shown below)

In the above screenshot, a coffee cup (with coffee) is a related item. Also, a Grouped
item called “Aerial View” is marked as related. Note that “Aerial View” is missing the
checkbox. This is because it is a Configurable Product, and cannot be added using
the checkbox, because the configurable attributes must be selected first.

Cross-Sells

Cross-sells display after a product has already been added to the shopping cart. In
this design package, three products are randomly picked from the products that are
marked as cross-sells of all the products in the shopping cart. To add cross-sell items to a product:

Log in to the Magento admin

Navigate to Catalog -> Manage Products

Find the product you want to add cross-sells to

Select and edit this product

Select the Cross-sells tab

From the products grid that appears, check any products you’d like to mark as cross-sells
(press “Reset Filter” to see all products)

Once a product has been checked, the “Position” field opens up. This determines the sort
order of the cross-sells in the shopping cart. If you have multiple products in the cart they
are randomly selected, so the sort order will not take effect.

Press “Save”

In the front-end, add the product you just edited to the shopping cart.

In the shopping cart you should now be able to see the cross-sells in the cross-sell block
as shown below: