Server-based and user-based methods
- server logs
- page counters (e.g. Nedstat - sometimes blocked, e.g. with Mozilla, Firebird, Safari)
- stats: hits, pageviews, unique visitors, time per visit
- cookies - count computers, not people
- software: Webtrends, Faststats (if still around)
- ethical problems: e.g. no informed consent by research companies (who should know better) - (block their cookies?)
- Cf. ESOMAR Code of Practice.
Chapter15 of Know Your Audience discusses the above issues in more detail.