Technical SEO also folds into the on-site implementations as it is the work that happens behind the scenes of your website. Changing headers, titles, and implementing keywords sound relatively easy once defined, however, there are clear mandates for effective on-site optimisations. The technical aspect also has to be taken into account for URL structures, canonicals and re-directs, etc. Amongst a vast myriad of ranking factors, Google's spiders do not like errors, slow websites, or deprecated links. Technical SEO digs into the detail and maintains the health of your website.