SEO glossary: key terms and definitions explaine

SEO (search engine optimisation) determines whether your business gets found when potential customers search on Google. Yet for many business owners, SEO is full of abbreviations and technical terms that make it hard to understand what is actually happening. This glossary was written by Karina Vester Schultz, the independent SEO and marketing consultant behind Vester Marketing, with over 10 years of experience from international companies. The purpose is to give you clear, precise definitions and written for people, not for search engines.

Core SEO concepts

Read up on the basic definitions in SEO so you know what it’s all about when you talk to a marketing agency.

What is SEO?

SEO is the process of improving a website’s visibility in search engines’ organic, that is, unpaid, results. The goal of SEO is to ensure that relevant users find a given website when they search for the products, services, or information it provides. SEO is typically divided into three sub-disciplines: technical SEO, on-page SEO, and off-page SEO.

What is technical SEO?

Technical SEO is the optimisation of a website’s technical characteristics that affect search engines’ ability to crawl, understand, and index the site. Technical SEO covers page speed, mobile optimisation, security (HTTPS), correct configuration of robots.txt and XML sitemaps, structured data, and implementation of hreflang on multilingual sites. A technically sound website is the prerequisite for all other SEO work to deliver results.

What is on-page SEO?

On-page SEO is the optimisation of the content and HTML elements visible on individual pages of a website. On-page SEO covers title tags, meta descriptions, heading hierarchy (H1–H3), internal link structure, keyword usage in body text, and image alt text. The purpose of on-page SEO is to clearly signal to search engines what a page is about, and to deliver the precise answer the user is searching for.

What is off-page SEO, and what are backlinks?

Off-page SEO refers to factors outside the website itself that influence its authority in search engine algorithms. The most important element in off-page SEO is backlinks: links from other websites to yours. Backlinks function as endorsements in Google’s eyes; the more credible and relevant websites that link to you, the more domain authority you signal. The quality of the linking sites matters far more than quantity alone.

What is a SERP?

A SERP (Search Engine Results Page) is the results page that a search engine, such as Google, displays after a user performs a search. A modern Google SERP can contain organic results, paid ads (Google Ads), featured snippets, AI Overview (AI-generated answers), knowledge panels, images, and local map results. The position of a given URL in the SERP depends on the search engine’s ranking algorithm and a large number of ranking factors.

What is organic traffic?

Organic traffic is the visitors who find a website through unpaid search engine results. Organic traffic is the outcome of SEO work and differs from paid traffic generated via Google Ads campaigns. One of the central advantages of organic traffic is that it does not stop when you stop paying; instead, it depends on the website’s ongoing visibility in search results.

What is search intent?

Search intent describes the underlying purpose behind a user’s search query. Google categorises search intent into four types: informational (the user wants to learn something), navigational (the user wants to find a specific page), transactional (the user wants to make a purchase), and commercial investigation (the user is comparing options before a purchase decision). A page’s ability to rank for a given keyword depends heavily on how well its content matches the underlying search intent.

What is keyword research?

Keyword research is the process of systematically identifying the words and phrases a target audience uses in search engines. Thorough keyword research reveals search volume, competitive intensity, and search intent for each keyword – and forms the foundation for on-page SEO, content planning, and SEM campaigns. Keyword research is the basis of all strategic SEO planning.

What are long-tail keywords?

Long-tail keywords are specific search phrases that typically consist of three or more words, have lower search volume than broad keywords, but often have a significantly higher conversion rate. The reason is that a user searching on a long-tail keyword typically knows exactly what they are looking for. For example, the keyword “SEO” is broad and competitive, while “SEO consultant for Danish B2B businesses” is a long-tail keyword with lower competition and higher action intent.

Technical SEO terms

Read up on the basics of technical SEO so you know what it’s all about when you talk to a marketing agency.

What are Core Web Vitals?

Core Web Vitals are a set of three performance measurements defined by Google that assess the user experience on a website. The three measurements are: LCP (Largest Contentful Paint), which measures the loading time of the largest visible element on the page; INP (Interaction to Next Paint), which measures the page’s response time to user interactions; and CLS (Cumulative Layout Shift), which measures visual stability during page loading. Core Web Vitals are an official ranking factor in Google’s algorithm.

What is hreflang?

Hreflang is an HTML attribute that signals to search engines which language or country version of a page should be shown to users in specific language groups or geographic regions. Hreflang is essential for international websites with content in multiple languages, as it prevents search engines from showing the wrong language version to the wrong users. Correct hreflang implementation requires all language variants to cross-reference each other through annotations in the HTML code or XML sitemap.

What is Schema.org and structured data?

Schema.org is a standardised vocabulary for structured markup, typically implemented as JSON-LD in a page’s HTML code. Structured data from Schema.org allows search engines and AI engines to explicitly understand the context of a content element: what a business is called, who runs it, what services it offers, and how customers rate it. Correct Schema.org implementation can result in rich snippets in search results and significantly increase the likelihood of being cited as a source in AI-generated answers.

What is robots.txt?

robots.txt is a text file placed at the root of a website that instructs search engine crawlers which pages, directories, or resources may and may not be accessed and indexed. An incorrectly configured robots.txt can inadvertently block important pages from being indexed, removing them from search results entirely. robots.txt is one of the first elements reviewed in a technical SEO audit.

What is an XML sitemap?

An XML sitemap is a structured file that lists all the URLs on a website that the owner wants search engines to index and prioritise. XML sitemaps help Google and other search engines discover and crawl new or updated pages more efficiently, particularly on larger websites or sites with complex navigation. XML sitemaps are typically submitted through Google Search Console.

What is a canonical tag?

A canonical tag (the HTML attribute rel=”canonical”) indicates to search engines which URL is the primary (canonical) version when the same or very similar content can be accessed via multiple URLs. Canonical tags are used to prevent duplicate content issues that arise when search engines index the same page under multiple addresses, which splits the ranking signal.

What is Open Graph?

Open Graph is a set of protocols that controls how a web page appears when shared on social media such as Facebook and LinkedIn which includes title, description, and the associated image. Open Graph tags are not a direct ranking factor in Google’s algorithm, but they influence click-through rates and visual presentation on social platforms, which can indirectly increase traffic.

AI search and GEO terms

Here you can read about the latest developments in AI and the terminology used.

What is GEO (Generative Engine Optimisation)?

GEO (Generative Engine Optimisation) is the discipline of optimising web content so that it can be identified and used as a source in AI-generated answers from platforms such as Google AI Overview, ChatGPT, Perplexity, and Claude. GEO builds on the principles of traditional SEO, but places heightened demands on content structure: each section should be able to stand as a standalone, authoritative answer, entities must be named explicitly, and structured data must be correctly implemented. Karina Vester Schultz at Vester Marketing works professionally with GEO optimisation as part of her consulting practice.

What is an LLM?

An LLM (Large Language Model) is the AI technology that forms the foundation of AI search engines and chatbots such as ChatGPT (OpenAI), Google Gemini, and Claude (Anthropic). An LLM generates language responses based on patterns in very large amounts of training text and applies those patterns to formulate answers to user queries. For SEO and GEO, it is relevant to understand that LLMs actively select and cite external sources in their answers, and that this citation probability is influenced by content structure, authority, and entity density.

What is Google AI Overview?

Google AI Overview (formerly called SGE – Search Generative Experience) is Google’s AI-generated answer box that appears at the top of search results for selected queries. AI Overview presents a summary of answers with source references, generated by Google’s Gemini model. Being cited in Google AI Overview requires content with high entity density, correctly implemented structured data, and sections formulated as precise, factual answers.

What is passage indexing?

Passage indexing is Google’s technology for indexing and ranking specific passages from a page independently of the page’s overall ranking. This means that a single well-formulated paragraph can be extracted and used as a source in a search result or AI-generated answer, even if the rest of the page is less relevant to the specific search query. Passage indexing is one of the reasons why each section in GEO-optimised content should be written as a standalone, complete answer.

What is entity optimisation?

Entity optimisation is the process of ensuring that named objects in a website’s content are people, businesses, places, products, and processes, are explicitly named and contextualised in a way that search engines and AI engines can recognise and understand. Examples of entities in the context of Vester Marketing include: Karina Vester Schultz (person), Vester Marketing (business), and GEO (discipline). Clear entity density in content is a central signal to AI engines that a source is credible and authoritative.

What is semantic SEO?

Semantic SEO is the approach of optimising content based on topics, relationships, and context rather than isolated keywords. Instead of repeating one keyword many times, semantic SEO involves covering a topic in depth using related concepts, synonyms, examples, and sub-questions in a way that is meaningful for human readers and understandable for AI engines. Semantic SEO supports both traditional rankings and GEO.

Local SEO

Is local SEO a must for you? The short answer is yes. Here you can read more about the various concepts.

What is local SEO?

Local SEO is search engine optimisation focused on improving a business’s visibility in local search results,s which is typically geography-based searches such as “[service] in [city]” and positions in Google Maps. Local SEO is particularly relevant for businesses that serve customers within a specific geographic area or that have a physical address. The most important factors in local SEO are an optimised Google Business Profile and NAP consistency across all platforms.

What is Google Business Profile?

Google Business Profile (formerly Google My Business) is a free business profile in Google’s local search results and Google Maps. A fully optimised Google Business Profile with accurate contact details, opening hours, categories, images, and regular customer reviews is the most central element in local SEO. Google Business Profile gives businesses the ability to appear prominently in local searches – even without a highly ranked website.

What is NAP consistency?

NAP consistency refers to the uniformity of a business’s Name, Address, and Phone number across all online platforms: website, Google Business Profile, social media, and industry directories. Inconsistent NAP information sends conflicting signals to Google and can weaken a business’s local SEO ranking.

SEM and paid search

SEM encompasses both SEO and SEA. SEA refers to paying to appear in Google search results. You can read more about the individual definitions here. 

What is SEM?

SEM (Search Engine Marketing) is the term for paid visibility in search engines, primarily through Google Ads. SEM gives businesses the ability to show ads at the top of search results for selected keywords in exchange for payment per click (CPC – Cost Per Click). SEM is particularly effective for product launches, seasonal campaigns, and in competitive markets where organic SEO takes a long time to build.

What is SEA?

SEA (Search Engine Advertising) is often used synonymously with SEM and covers specifically paid text ads in search results. Via Google Ads, the advertiser bids on keywords and pays a price per click (CPC) that depends on competition for that keyword and the ad’s Quality Score.

What is Quality Score in Google Ads?

Quality Score is Google’s assessment of the relevance and quality of a Google Ads ad and the landing page it points to. Quality Score is calculated on a scale from 1 to 10 and directly affects the ad’s cost per click and position in search results. A high Quality Score is achieved through close alignment between the keyword, the ad copy, and the content of the landing page.

What are negative keywords?

Negative keywords are search terms that are actively excluded from a Google Ads campaign so that ads are not shown for irrelevant queries. Correct use of negative keywords is essential for avoiding wasted budget and ensuring that the ad spend is used exclusively on searches with genuine conversion potential.

Analytics and measurement

It’s always important to figure out what works; that’s why you should always analyze and track your KPIs (key performance indicators) for your initiatives.

What is Google Search Console?

Google Search Console is a free webmaster tool from Google that provides insight into how a website performs in Google search. Via Google Search Console, you can see which search terms generate impressions and clicks, which pages are indexed, and whether there are crawl errors, hreflang errors, or security issues affecting visibility.

What is CTR?

CTR (Click-Through Rate) is the percentage of users who click on a given search result listing after seeing it in the SERP. CTR is calculated as (clicks/impressions) x 100. A high CTR indicates that the page’s title and meta description are relevant and appealing to users, and it is a signal that can positively influence the page’s rankings over time.

What is domain authority?

Domain Authority is an estimated ranking measure developed by SEO platforms such as Moz and Ahrefs. It assesses how likely a website is to rank well in search results, based primarily on the strength and composition of its backlink profile. Domain Authority is not an official Google metric, but it is used in the industry as a useful comparative benchmark.

Do you want help putting these concepts into practice?

Vester Marketing helps SMBs apply SEO and GEO in concrete terms everyhing from technical setup to content optimisation. Contact Karina Vester Schultz for a no-obligation conversation.