When I tell people what I do for a living, the first question is always 'how long should my resume be?'. They usually also ask if it's true that modern resumes are only meant to be one page. (This is usually said with mild panic... how on earth are you supposed to get a resume down to one page?!)
Well, the good news is that in Australia resumes are normally longer than one page. In North America a one page resume is common. And a North American resume is different from a CV, which is essentially a very long career history...
In Australia we use the terms CV or resume interchangeably. Your resume will be longer than one page, and I don't recommend going over four pages unless you are a published academic or researcher. I would recommend three pages if you are early in your career, and four pages if you are mid-late career.
So, why have you heard about the one page resume? Because the front page of your resume should be a nice summary document, which could be viewed as a standalone document. On your first page you should include:
Your name and contact details
A professional profile
A skills/strengths summary
Key Achievements from across your career
A career summary (list of jobs and years)
This front page needs to really sell you to the prospective employer. They need to quickly and clearly see that you have the skills to do the job, and your achievements need to make you stand out from the crowd.
A great first page will make them want to read on for further details, and want to meet you at an interview.
Pages 2-3 of your resume will include your career history (responsibilities and achievements for each job) followed by Education and Training, Other Relevant Information (including Volunteer Work), and References.
If you are finding you can't fit everything into four pages, you will need to remove the detail from older jobs (I suggest jobs you did more than 12-15 years ago can be listed as "Earlier roles included:" and just list the job title and organisation. And you can remove really old or completely irrelevant jobs altogether. For example, I used to work in hospitality but this is not on my resume.
So next time you are at a dinner party and job hunting and resumes come up in conversation, you can confidently discuss the merits of the one page North American resume versus the Australian four pager with the 'one page' front page!