When You Encounter "Bandwidth" or "TTL" and Aren't Sure What They Mean
In your hosting control panel or purchase invoice, you see terms whose exact meaning you guess at—but if you misunderstand them, you'll pay the price. "Bandwidth" is different from "Traffic." "SSL" is not the same as "HTTPS." And "DNS" is not at all where your site stores its files. This glossary is for someone who knows what they're looking for and wants a formal, precise definition—not extra explanation.
I've started each term with a short definition, and where more detailed explanation is warranted, I've linked to the relevant document in the Documentation and Knowledge Base.
Basic Terms: Hosting, Server, Domain
Hosting
Space on a server where your site's files (HTML, images, scripts) are stored and sent in response to browser requests. "Shared hosting" means multiple sites on one physical server with shared resources. "Virtual Private Server" (VPS) means an isolated partition with dedicated resources on a physical server. "Dedicated server" means the entire hardware is yours.
The practical difference between these three lies in resources and isolation. On shared hosting, if your neighbor's site gets a sudden traffic spike, your site slows down. This doesn't happen on a VPS because your CPU and RAM are allocated separately. Read the guide to choosing between these options in the Comprehensive Guide to Choosing a Hosting Service.
Domain
The textual address of your site, such as example.com. A domain resolves to an IP address that identifies the actual server. The domain itself stores no files; it's just a record in the DNS system that says "this name points to which IP."
This is where people make mistakes: many think that if they don't renew their domain, the site just goes offline. No. If the domain expires and someone else buys it, your entire digital identity (domain-based emails, SEO history, brand credibility) falls into their hands. Set your domain renewal to auto-pay.
Bandwidth and Traffic
Bandwidth is the maximum amount of data that can be transferred in one second (unit: Mbps). Traffic is the total volume of data transferred in a month (unit: GB). Don't confuse the two.
Example: a site with 1,000 daily visits and an average of 2 MB per page consumes about 60 GB of traffic per month. If your plan has 50 GB of traffic, your site will go offline on the 25th day of the month, or you'll pay overage charges. Always estimate your plan's traffic with the formula "daily visits × page size × 30."
Technical Terms: DNS, SSL, FTP
DNS (Domain Name System)
The internet's phone system. When you type example.com, the browser asks a DNS server "which IP does this name point to?" and then sends a request to that IP. DNS is a distributed database, not a central server.
DNS records come in various types: an A record maps a name to IPv4, an AAAA record to IPv6, an MX record to the mail server, and a CNAME record to another name. DNS changes take between 4 and 24 hours to propagate across the entire internet. This delay is called "DNS propagation" and can be shortened by lowering the TTL (below 300 seconds), but at the cost of more load on the DNS server.
SSL and HTTPS
SSL (Secure Sockets Layer) is a protocol that encrypts the connection between the browser and the server. HTTPS is the secure version of HTTP that uses SSL/TLS. The difference: SSL is the protocol itself; HTTPS is the result of using it on the web.
There are three types of SSL certificates: Domain Validation (DV), which only verifies domain ownership; Organization Validation (OV), which also checks the organization's identity; and Extended Validation (EV), which offers the highest level of trust and displays the organization's name in the address bar. For an e-commerce site, a DV certificate with 256-bit encryption is sufficient. An EV certificate is only worth the extra cost for sites where user trust is critical (banks, payment gateways).
If your site still runs on HTTP and the browser shows "Not Secure," this is the first technical step you should take. The free Let's Encrypt certificate is sufficient for most sites and renews every 90 days.
FTP and SFTP
FTP (File Transfer Protocol) is a protocol for uploading and downloading files to a server. SFTP is its secure version, which uses SSH for encryption. Never use plain FTP; your username and password are sent as plain text over the network, and anyone along the path can read them.
The default port for FTP is port 21, and SFTP uses port 22. If your host supports SFTP (and almost all do), use it. If you're forced to use FTP, at least change your password every month.
Resource Terms: RAM, CPU, NVMe
RAM and CPU
RAM is temporary memory that programs use while running. CPU is the processor that executes instructions. On shared hosting, these resources are divided among all sites on the server. On a VPS, your share is guaranteed.
A rule of thumb: WordPress runs on 512 MB of RAM but is comfortable with 1 GB. If you use Page Cache, you can get by with 256 MB. But if you have WooCommerce with 1,000 products, consider 2 GB as the minimum budget.
NVMe and SSD
Both are types of permanent storage, but NVMe (Non-Volatile Memory Express) uses the PCIe protocol and has 3 to 5 times the read/write speed of a regular SSD (SATA). Real numbers: a SATA SSD has about 550 MB/s sequential read speed, while a third-generation NVMe has about 3,500 MB/s. The difference is clearly noticeable on database-driven sites (WooCommerce, WordPress with many plugins).
If you're choosing between a host with SSD and one with NVMe, and the price difference is less than 30%, choose NVMe. Lower database read latency means lower TTFB and a better user experience. But if your site is static (no database), SSD is sufficient, and the extra cost of NVMe isn't justified.
Management Terms: cPanel, DirectAdmin, SSH
cPanel and DirectAdmin
Both are hosting control panels that let you create emails, manage databases, upload files, and add domains. cPanel is more popular, and most tutorials are written for it. DirectAdmin is lighter and consumes fewer resources.
Practical difference: cPanel is more common on shared servers and has more plugins. DirectAdmin is lighter for VPS and runs even on 512 MB of RAM. If you're going to manage things yourself and lack experience, cPanel is the safer choice because it has more documentation and video tutorials.
SSH (Secure Shell)
A protocol for securely connecting to the server's command line. With SSH, you can run commands, edit files, and manage services. Unlike FTP, which only moves files, SSH gives you a full shell.
Example command: ssh root@203.0.113.10 -p 22 with a public key instead of a password. If your host offers SSH, learning its basics is worth it. For file management over SSH, learn the command rsync -avz --progress /local/path user@server:/remote/path; this tool is the best option for transferring a site between servers. See the complete checklist for a zero-downtime migration in the ServerNet Migration Documentation.
Email Terms: MX, SPF, DKIM
MX Record
A DNS record that specifies which server a domain's emails should be delivered to. If you configure MX incorrectly, your emails will go to the wrong server or bounce back.
This is where people make mistakes: many, after migrating hosting, only change the site's DNS and forget the MX record. Result: the site comes up, but emails still go to the old server, and after the old service is cut off, all emails are lost. Before migrating, export a complete list of your DNS records.
SPF and DKIM
SPF (Sender Policy Framework) is a record that specifies which servers are authorized to send email on behalf of your domain. DKIM (DomainKeys Identified Mail) is a digital signature that verifies an email was actually sent from your server and wasn't tampered with along the way.
Without these two, your emails will go to spam or be rejected outright. Example SPF record: v=spf1 include:spf.example.com ~all. The ~all flag means "soft-fail emails coming from other servers," while -all means "hard-fail." For an e-commerce site, -all is safer, but if you use an email marketing service, be sure to add its IP to your SPF record—otherwise, your promotional emails will also be rejected.
Performance Terms: TTFB, Latency, Uptime
TTFB (Time To First Byte)
The time that passes from the browser sending a request to receiving the first byte of the response from the server. This metric shows how quickly the server responds, not how quickly content loads. A TTFB under 200 milliseconds is good; above 500 milliseconds requires investigation.
High TTFB usually comes from three sources: slow DNS, a busy server, or heavy server-side code. To diagnose, use curl -w "%{time_starttransfer}" -o /dev/null https://example.com. If TTFB is high but the site is lightweight, the problem is the hosting.
Uptime
The percentage of time a site has been available. 99.9% uptime means about 8.7 hours of downtime per year. 99.95% means 4.3 hours. The difference seems small, but for an e-commerce site with daily revenue, even those few hours mean losing real sales.
No host has 100% uptime. The right question isn't "do you have outages?" but rather "when an outage occurs, how long does it take you to find out, and what response time do you promise for fixing it?" Write the answer to this question into the SLA and read it before purchasing.
Frequently Asked Questions
What's the difference between shared hosting and a VPS?
On shared hosting, server resources (CPU, RAM, disk) are divided among multiple sites, and your performance depends on your neighbors. On a VPS, resources are dedicated to you and isolated. If your site has variable traffic or uses heavy scripts, a VPS is the better choice.
Why should I lower TTL, and when shouldn't I?
A low TTL (e.g., 300 seconds) means DNS changes propagate faster, but your DNS server receives more requests. If you're planning a server migration, lower the TTL 24 hours beforehand so the site moves to the new server quickly after the change. If you don't make frequent DNS changes, the default TTL (3,600 seconds) is sufficient.
How do I find out how much traffic my hosting has consumed?
In your hosting control panel (cPanel or DirectAdmin), open the "Bandwidth" or "Traffic" section. It usually shows daily and monthly statistics with charts. If you're approaching the limit, first remove large files (videos, archives) from the host, and if the problem persists, upgrade your plan.
Is a free SSL certificate secure?
Yes. A Let's Encrypt certificate is no different from paid certificates in terms of encryption; both use the TLS standard. The difference is in the level of identity verification: a free certificate only verifies domain ownership, while an organizational certificate also verifies the company's identity. For a regular site, a free certificate is completely sufficient.
If you're just getting started and want to know which service suits you, read the Guide to Choosing a Hosting Service. And if you have a question you didn't find answered here, see the Guide to Writing Effective Support Tickets to get the fastest possible response.