In most cases, shared hosting will be among the most affordable. Service providers such as GoDaddy, Bluehost, and 1&1 will offer shared hosting, some as low as one dollar a month.
Shared hosting is typically best for websites that are built entirely in HTML and do not heavily rely on the database. Shared plans typically lack in the resource department and are often underpowered when it comes amount of available memory.
Memory is an important asset that a database driven content management system such as Drupal depends on for optimal performance, and a lower amount of available memory will reduce the number modules that can be used. In addition to less modules, low memory will also contribute to longer page loads.
In some cases the memory limit can be upgraded via modifying your .htaccess, but generally the maximum amount is far less than what may be available with alternative forms of hosting.
In addition to low availability of system resources, shared hosting also provides limited access to the server. Installing additional packages may require contacting the provider, applying custom configurations, and in some cases installing third party software is impossible.
Virtually all shared hosting will provide FTP access, however access to the secure shell (SSH) is often limited. Where some providers allow you limited SSH access some providers will restrict it entirely, meaning that using tools like Drush will not be an option.