I'm currently working on the wireframes of a webshop for a chain of electronics stores (TV's, washing machines, etc). Users can place products in the shopping cart and start the checkout process from the shopping cart; nothing fancy, basically your default webshop.
Consider the following option's:
The shopping cart page is not part of the checkout process. The checkout process is divided up in steps (1, 2 and 3). The shopping cart features a button that initiates the checkout process (e.g. 'checkout')
The shopping cart page is part of the checkout process and displays the checkout steps (1, 2, 3 and 4) somewhere on the page. The shopping cart features a button that initiates the checkout process (e.g. 'checkout')
I'm personally leaning towards option 1; the shopping cart is a place that the user uses to gather his products. He's going to visit the page more then once, reviewing his order and finally to decide on continuing the actual process of ordering the order.
To have the shopping cart as part of the checkout process feels wrong because of the way it gets used. Clicking 'add to cart' on a product page is not the start of the checkout process; you're simply placing a product in the cart. Only when you're ready to order would the user initiate the checkout process, from the shopping cart.
A colleague of mine does favor towards option 2, because it gives more insight in the checkout process.
So I'm wondering, what's the best place for a shopping cart in the checkout process as a whole?