SEO is first and foremost a marketing activity. However, because it is web-based, there are a number of technical aspects inherent to the job. An SEO person must posses HTML expertise (webpage language), PHP skill (a common programming language used on websites), and have a good understanding of DNS (how the web finds your website).
So just how far do the responsibilities of an SEO person extend?
This is industry expert Rand Fishkin’s take on this topic:
Where I try to draw the line between SEO and general support is to ask the question “does the activity doesn’t have a direct impact on the marketing of the website”. Sure I can edit copy and change a phone number, I can add an email account and change passwords, and even backup your website, but those are not really “marketing” tasks and are probably better and more economically accomplished by an IT person or Webmaster who does those tasks on a daily basis.
For customers who don’t have an IT person, I can help connect you with someone locally who does these things on a routine basis and act as a bridge when “who does what ” is unclear.