You will need a domain name. This is the name of your website eg www.yourbusiness.biz. See my full article on 'Buying a Domain Name.'
This is where your files are stored. Hosting can be from the same company as your domain name, or elsewhere. I evaluate the fastest hosting providers in the world for value for money and performance, and work with the best solution for you. Do feel free to ask me if you have any questions about the relative advantages of different hosts.
Your email service where your emails will be stored and sent from. This may be the same company as your host, your domain name registrar or somewhere else! I recommend using a service such as gmail for business. I can provide basic email services on request. Please ask me about the associated fees.
Content Management System
Do you want to edit your website yourself? Your content (text, images etc) need to be organised and stored in a way that makes it really easy for you to manage. Hence websites use a Content Management System (CMS). I have experience with well know systems such as Wordpress, Joomla and various other systems. Your CMS will normally need to be customised to suit the type of data or content that you wish to display on your site. Think beyond just web pages. Do you need blogs, calendars, events, news items? Do you want to display people in your team? The latest project? How often will this information change? Will that be done manually or will publishing be scheduled? Will it be displayed in order of date? Do you want the user to be able to sort and filter the content on your site somehow? All these considerations are related to the setup of your site CMS. Be careful before choosing a 'free' CMS or before accepting a quote for your website. Make sure you specify what is required, perhaps by referencing example sites you like. Not all systems are equal, and once you've set your site up one way, it can be hard to change to another system.
Try to plan ahead - you might only want a simple site now but your business or organisation's needs may well change rapidly over time. Try to plan for this and ask questions about what your cms can do for you in the future.
It's always worth considering if and how you connect your website to blogs, social media accounts, email marketing systems, and other automated business services.