SSL Certificate

Two things. Every modern browser marks the site "Not secure", which makes visitors leave immediately, and Google has used HTTPS as a ranking signal since 2014, so a plain HTTP site is at a disadvantage in both trust and search position.

Positive SSL (฿600/year) covers one domain, meaning both site.com and www.site.com. That is right for a normal site on a single domain. Wildcard (฿3,600/year) additionally covers unlimited subdomains such as blog.site.com, shop.site.com and mail.site.com. Wildcard pays for itself from roughly 3-4 subdomains onward, since buying separate certificates for each would cost more.

DV confirms that you control the domain, and it is the level most sites on the internet use. The encryption between visitor and site is exactly as strong as on higher-tier certificates — 256-bit encryption on the 2048-bit standard in both cases. What differs is the level of organisational identity checking, which only matters for banks and large organisations that want their company name shown on the certificate.

On hosting with DirectAdmin or cPanel there is a menu for pasting the certificate in — a few clicks. On a VPS you manage yourself, you edit the Nginx or Apache configuration by hand. Support is available 24 hours a day if you get stuck.

The browser shows a full-page warning that the connection is not secure, and visitors have to click through it to reach your site — almost all of them go back instead. Set a renewal reminder at least two weeks before the expiry date.

On encryption strength, a free certificate such as Let's Encrypt is equivalent. The differences are certificate lifetime (free ones typically last 90 days and rely on auto-renewal that breaks if it is misconfigured), Wildcard coverage being harder to set up, and having someone to call when it goes wrong. For a personal site with working auto-renewal, free is fine. For a business site that cannot afford downtime, ฿600 a year to remove that risk is cheap.