How do I add custom product page tabs?

You can create tabs in two different ways:

1. Using a page, shown on all product pages.
   
   or
2. Using metafields, shown only on products with metafield values.

I want to show the tab on all product pages

This is the easiest option to set up and is useful for general product information like shipping and return policies, universal size charts, and anything else that applies to your entire product line.

1. In the theme editor, navigate to the Product page template by clicking on Products, then Default product from the page selector.
2. Under the Product section in the left sidebar, click on Add Block. If you don't see this option, you may need to hover your mouse pointer between existing blocks. A blue plus (+) button should appear, allowing you to add a new block. 
3. Select the Tab block and position it as desired within your product template.

This tab and the content you include in the block settings will appear for all products assigned to use this template.

I want to show the tab on specific product pages

Create product metafields

Text content only:

1. From your Shopify admin, go to Settings > Metafields and metaobjects, then select Products under Metafield definitions.
2. Click Add definition to create a new metafield. You’ll need to create two metafields for each tab: use a single-line text metafield for the tab title and a multi-line text metafield for the tab content.

Tab content with images: 

If you’d like to include images or tables in the tab content, we recommend adding the content in a custom page (Online Store > Pages) and then referencing that page in the tab using a metafield.

1. From your Shopify admin, go to Settings > Metafields and metaobjects, then select Products under Metafield definitions.
2. Click Add definition to create a new metafield. You’ll need to create two metafields for each tab: use a single-line text metafield for the tab title and a page reference metafield for the tab content.

Repeat this process for each tab you want to add. For example, creating two tabs requires four metafields.

Assign metafield values

1. In your Shopify admin, go to Products and open the product you'd like to add the product tab.
2. Scroll to the Product metafields section, enter content for the metafields, and click Save.

Add tab in the product page

Text content only:

1. In the theme editor, navigate to the Product page template by clicking on Products, then Default product from the page selector.
2. Under the Product section in the left sidebar, click on Add Block. If you don't see this option, you may need to hover your mouse pointer between existing blocks. A blue plus (+) button should appear, allowing you to add a new block. 
3. Select the Tab block and position it as desired within your product template.
4. Use the Connect dynamic source (database icon) and click on Tab content from page.
   
5. Click Template > Products to view the available product metafields. 
    
6. Select the metafield you want to connect to the tab.
7. Repeat these steps to link a metafield to both the tab title and tab content.

Tab content with images: 

1. In the theme editor, navigate to the Product page template by clicking on Products, then Default product from the page selector.
2. Under the Product section in the left sidebar, click on Add Block. If you don't see this option, you may need to hover your mouse pointer between existing blocks. A blue plus (+) button should appear, allowing you to add a new block. 
3. Select the Tab block and position it as desired within your product template.
4. For the heading text, use the Connect dynamic source (database icon) and click on Tab content from page.
   
5. Click Template > Products to view the available product metafields. 
    
6. Select the metafield you want to connect to the tab.
7. For the tab content, click the Connect dynamic source (database icon) next to Tab content from page, then select the page reference metafield you want to use.
   

Here's a video that shows you step-by-step how to set up custom product tabs using metafields so that they appear only on specific product pages.