A website is really four things: the domain name, the hosting, the files and content, and the accounts connected to it. Most business owners assume they own all four. Plenty find out otherwise on the worst possible day, when a designer stops answering, an agency closes, or the relative who set everything up moves on.
Getting control back is possible but slow. Getting it right from the start takes an afternoon.
The domain matters most
Your domain is your address, your email, and years of search history. Whoever is listed as the registrant on the domain record is treated as its owner. That should be you or your company, with an email address you'll still have in ten years. Not your designer's agency. Not a former employee's personal Gmail.
To check, log into the registrar where the domain is held, or ask whoever manages it which registrar that is. Look at the registrant contact. If it isn't you, ask for the domain to be moved into an account in your name. A reputable designer will do it without argument.
Turn on auto-renew and keep a current card on file. Expired domains get picked up by resellers, and buying one back is expensive and slow.
Hosting can be shared, but you should hold a key
It's normal for a designer to manage hosting, and often better, since they're the one keeping it updated. What matters is that you could get a full copy of your website if you needed it. Ask: if we parted ways tomorrow, how would I get my files and database? The answer should be simple and immediate.
If you pay for hosting directly, keep the login in a password manager and add your designer as their own user instead of handing over your credentials.
Know where your content lives
On WordPress, the website is yours: the files and database can move to any host. On hosted builders like Wix or Squarespace, the design generally can't leave the platform, though the content can be copied out. That's the difference between owning and renting a website, and it's worth knowing which one you have before you need to move.
The accounts people forget
Google Business Profile. Google Analytics and Search Console. Your email provider. Social profiles. Any payment processor connected to the website. Each should list you, or a company account, as the owner, with your designer added as a manager. An owner can add and remove everyone else; a manager can't remove the owner.
Write it down
Make one document that lists every account, who owns it, where the login lives, and when it renews. Store it somewhere you'll find it in three years. It takes an hour and saves days if something ever goes wrong.
When we build a website, the domain, hosting access, and every connected account are set up in the client's name from day one. If a designer resists doing the same, pay attention to that before you sign. Our notes on what happens after launch cover the rest of a proper handoff.