This is the name of your website, usually your company name or relating to your product or a trading name, it is important to secure the domain name at the earliest available time, you don't have to make any other decisions at this stage.
Unfortunately parties do register a variety of names that they think are popular so they can resell them for profit, your company name is normally a part of your branding so protect it as soon as you can.
Contrary to various charges made by web design companies domain names are relatively inexpensive, a few pounds for a .co.uk a few more for .com.
What do the extensions mean .co.uk .com etc. we'll explain that and suggest the best options for you.
You don't have to have the same Internet Service Provider (ISP) and website host, there are a few things to consider. Often companies charge a premium for domain names while offering a competive hosting fee knowing that you'll pay to avoid any problems and save time.
Generally we'll suggest using a simple easy to remember name, people generally don't want to type more than they have to, if the spelling is obscure will people remember what to type?