Dedicated Server - a kind of hosting, in which a dedicated physical server is provided for use by the client. Its owner gets full administrative access to the machine, can install any operating systems, including non-standard builds of distributions, and also has the ability to make changes to the BIOS settings. Typically, dedicated servers are used to deploy complex projects (for example, corporate portals with back-office functions for employees), cloud services, and high-performance business applications.
Shared hosting involves placing a large number of sites within a single hardware and software platform. In other words, one physical server provides dozens and hundreds of independent sites. Being the cheapest, it is ideal for beginner projects and sites with low traffic (business cards, portfolio), but it also has a number of limitations. Unlike VPS / VDS, users of shared tariffs do not have the ability to change software settings (as a rule, business is limited only by htaccess directives), add specific libraries or modify the kernel of the operating system. In addition, server resources are distributed evenly among all participants, which can lead to serious performance degradation.
VDS / VPS is a service where each hosting client gets at his disposal his own virtual machine, which is controlled in exactly the same way as working with a physical one. The presence of root access (provides super administrator rights) allows you to make almost any changes to the settings and composition of existing software. At the same time, the cost of a virtual VPS server is much lower than a dedicated lease, which makes it an ideal transitional option for dynamically developing projects and hosting applications that present specific requirements for the software environment.