Search engine optimisation

What is search engine optimisation?

Search engine optimisation (SEO) is the process of making a web page show on a search engine’s results. When you search using a search engine, the better optimised the page, the higher up it shows on the list of results. This works for searches within a website, and using a search engine. The three most important sections are the keywords, metadata description and titles.


These are words or phrases which are relevant to the content. Search engines use these to rank the contents of a page. Check if your website has a synonym list, as this will show words which are related and linked together automatically, such as “GDP” and “gross domestic product”. These words should not be added in separately.

When writing keywords:

  • use a maximum of five keywords (too many will push the content further down search results)
  • make sure each word or phrase is no more than 30 characters long (including spaces)
  • include relevant words or phrases that are in your content
  • make sure keywords are specific and unique
  • research what search terms people use when looking for your content (sites such as Google Trends are useful here)
  • if you are using acronyms, include the acronym and the full name
  • check if your website has a synonym list before adding keywords
  • add the most important keywords into the title and URL of the release, and then any secondary keywords into the first paragraph
  • use lower case

Keywords should not:

  • repeat any words that are in the title of your content
  • include the singular and plural of a word, such as “property” and “properties”
  • include separate terms from phrases, such as “equality training” and “diversity training” when referring to “equality and diversity training”

Metadata descriptions

The metadata description is the summary of the release content. It is mainly used for search purposes and should be searchable. This can make up the text that appears in search results. Users should be able to immediately understand what the link contains.

The description should:

  • be an accurate, concise and clear description of the content
  • be “frontloaded”, with a summary of the content at the start of the description
  • not start with phrases such as “This page provides…”
  • have a unique description that is specific to the content, which does not repeat the title
  • be no more than 160 characters including spaces (search engines ignore any text over this)


Titles appear in search results and should:

  • accurately describe the statistics, using plain English
  • include the geographical area and period covered by the content
  • be unique
  • use sentence case as this is easier to read, for example: “The adventure begins in earnest”

Inverted pyramid

This is the best practice style for web writing. The inverted pyramid means placing information in order of importance on the page.

The nub of the story – who, why what, where and when – appears in the first paragraphs so that the majority of users will see it. This should be a conclusion of the main facts. Other facts are included in descending order of importance down the page. This reflects the fact that most users on the ONS website read only the first section of a page and then leave.

The inverted pyramid structure is as follows:

  1. Most important information (who, what, when, where, why, how)
  2. Important details
  3. Other general or background information


Paragraphs should:

  • be tightly written with compact sentences that follow a logical order
  • be no more than six sentences
  • lead with a sentence that introduces the information contained in the paragraph, meaning readers can skim through the information
  • draw the reader on by making one paragraph lead naturally into the next
  • be able to make complete sense on its own
  • cover one subject

If a large chunk of text contains paragraphs on different topics, subdivide the chunk into different sections to make it easier to read.


Sentences should be no longer than 25 words. If they are any longer they need to be divided into two.

A sentence should not start with a figure. The sentence should be restructured.

Left-handed people make up 47% of the UK population.

For avoiding problems in construction see Do not under Plain English.

We are constantly improving based on research and best practice. Any significant changes to our guidance are available on the Updates page.