When we are quoting development work for prospective clients we are often asked to develop a website that is search engine optimized. This usually brings me into a long-winded explanation on how developing a website to be search engine friendly is not the same thing as optimizing that website for search performance; Kind of like how building a car is not the same as making it ready to compete in the Indy 500. Those are two different tasks altogether.
Let me explain.
The SEO provider or consultant should be involved in the website development process, though those two roles are completely different. The developer designs and creates the front and back end of the website. A good developer can do that job well, but mostly they do it to function for the user, not perform for the search engines. The SEO should be involved to ensure that what the developer produces is as search engine friendly as possible.
Most web design and development companies don't know the first thing about SEO or creating SE friendly websites. And most who claim to are liars. Sorry, but that's just the way it is.
Hint: If your web developer says they will SEO your website for you as part of the one-time design fee, they are a liar. If they tell you they'll develop a search engine friendly or SEO ready site then there is a better chance they know what they are talking about.
Let me be clear: Designing or programming a search engine optimized website simply cannot be done. Designing or programming a search engine friendly site can.
Design/development and SEO are two completely different things, though closely tied together. Each, however, requires a completely different skill set. Most SEOs don't claim to be web developers (though some are), but oddly, many web designers claim to be able to SEO (though most can't).
The process of SEO requires hours of additional research and a skill set that usually is not included as a part of the site development contract. There are a few development firms that also specialize in SEO and Marketing and these firms can develop and engage in long-term optimization services. But, be aware that any short-term website development contract that claims to include SEO simply will not provide adequate or successful SEO marketing results.
It's very smart to find a web developer that can create a search engine friendly website, but be aware of claims of SEO services being included. It's even smart to find an SEO that will work with your web developer to create a search engine friendly website that is completely compatible with their optimization processes. This prevents the SEO from having to ask for numerous and expensive site development changes in order to embark on a successful SEO campaign.