Steve Krug's first law of usability states the average website user's perspective succinctly - "Don't make me think!". The key concept in question here is cognitive load, a term used to define the amount of mental energy required to do something. This can be further broken down into intrinsic and extraneous cognitive load – intrinsic referring to the effort of absorbing new information, and extraneous being the mental processing that doesn’t help with understanding the content. People have a limited amount of mental energy available at any given time, so they naturally prefer the easier path, making it extremely important to minimise cognitive load as much as possible. Review your site and consider whether it’s obvious what each element does - the clearer the purpose or function of each element, the less mental energy you’re asking a user to expend on your site and the more likely they are to continue using it.