diff --git a/README.md b/README.md
index 4f3db0e..bf6eb4d 100644
--- a/README.md
+++ b/README.md
@@ -1,13 +1,13 @@
-# @chiffre/template-library
+# @chiffre/analytics-core
 
-[![NPM](https://img.shields.io/npm/v/@chiffre/template-library?color=red)](https://www.npmjs.com/package/@chiffre/template-library)
-[![MIT License](https://img.shields.io/github/license/chiffre-io/template-library.svg?color=blue)](https://github.com/chiffre-io/template-library/blob/next/LICENSE)
-[![Continuous Integration](https://github.com/chiffre-io/template-library/workflows/Continuous%20Integration/badge.svg?branch=next)](https://github.com/chiffre-io/template-library/actions)
-[![Coverage Status](https://coveralls.io/repos/github/chiffre-io/template-library/badge.svg?branch=next)](https://coveralls.io/github/chiffre-io/template-library?branch=next)
-[![Dependabot Status](https://api.dependabot.com/badges/status?host=github&repo=chiffre-io/template-library)](https://dependabot.com)
+[![NPM](https://img.shields.io/npm/v/@chiffre/analytics-core?color=red)](https://www.npmjs.com/package/@chiffre/analytics-core)
+[![MIT License](https://img.shields.io/github/license/chiffre-io/analytics-core.svg?color=blue)](https://github.com/chiffre-io/analytics-core/blob/next/LICENSE)
+[![Continuous Integration](https://github.com/chiffre-io/analytics-core/workflows/Continuous%20Integration/badge.svg?branch=next)](https://github.com/chiffre-io/analytics-core/actions)
+[![Coverage Status](https://coveralls.io/repos/github/chiffre-io/analytics-core/badge.svg?branch=next)](https://coveralls.io/github/chiffre-io/analytics-core?branch=next)
+[![Dependabot Status](https://api.dependabot.com/badges/status?host=github&repo=chiffre-io/analytics-core)](https://dependabot.com)
 
-Template for Chiffre libraries
+Types & definitions for Chiffre Analytics
 
 ## License
 
-[MIT](https://github.com/chiffre-io/template-library/blob/next/LICENSE) - Made with ❤️ by [François Best](https://francoisbest.com).
+[MIT](https://github.com/chiffre-io/analytics-core/blob/next/LICENSE) - Made with ❤️ by [François Best](https://francoisbest.com).
diff --git a/package.json b/package.json
index 6092987..1b213d7 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
-  "name": "@chiffre/template-library",
+  "name": "@chiffre/analytics-core",
   "version": "0.0.0-semantically-released",
-  "description": "Template for Chiffre libraries",
+  "description": "Types & definitions for Chiffre Analytics",
   "main": "dist/index.js",
   "license": "MIT",
   "author": {
@@ -11,11 +11,11 @@
   },
   "repository": {
     "type": "git",
-    "url": "https://github.com/chiffre-io/template-library"
+    "url": "https://github.com/chiffre-io/analytics-core"
   },
   "keywords": [
     "chiffre",
-    "template"
+    "analytics"
   ],
   "publishConfig": {
     "access": "public"
@@ -28,14 +28,15 @@
     "build": "run-s build:clean build:ts",
     "ci": "run-s build test"
   },
-  "dependencies": {},
+  "dependencies": {
+    "nanoid": "^2.1.11"
+  },
   "devDependencies": {
     "@commitlint/config-conventional": "^8.3.4",
-    "@types/faker": "^4.1.10",
     "@types/jest": "^25.1.4",
+    "@types/nanoid": "^2.1.0",
     "@types/node": "^13.9.1",
     "commitlint": "^8.3.5",
-    "faker": "^4.1.0",
     "husky": "^4.2.3",
     "jest": "^25.1.0",
     "npm-run-all": "^4.1.5",
@@ -46,7 +47,7 @@
   "jest": {
     "verbose": true,
     "preset": "ts-jest/presets/js-with-ts",
-    "testEnvironment": "node"
+    "testEnvironment": "jsdom"
   },
   "husky": {
     "hooks": {
diff --git a/src/events.ts b/src/events.ts
new file mode 100644
index 0000000..aecbb17
--- /dev/null
+++ b/src/events.ts
@@ -0,0 +1,132 @@
+import { SessionData } from './session'
+import { PageVisitData } from './navigation'
+
+export interface Event<T, K extends keyof T> {
+  type: K
+  time: number
+  data?: T[K]
+}
+
+// ---
+
+export interface GenericDataPoint<T, Meta = any> {
+  name: string
+  value: T
+  meta?: Meta
+}
+
+export type GenericEvents = {
+  'generic:number': GenericDataPoint<number>
+  'generic:numbers': GenericDataPoint<number>[]
+  'generic:string': GenericDataPoint<string>
+  'generic:strings': GenericDataPoint<string>[]
+}
+export type GenericEvent = Event<GenericEvents, keyof GenericEvents>
+
+export function isGenericEvent(event: AllEvents): event is GenericEvent {
+  return (
+    isGenericNumberEvent(event) ||
+    isGenericNumbersEvent(event) ||
+    isGenericStringEvent(event) ||
+    isGenericStringsEvent(event)
+  )
+}
+export function isGenericNumberEvent(
+  event: AllEvents
+): event is Event<GenericEvents, 'generic:number'> {
+  return event.type === 'generic:number'
+}
+export function isGenericNumbersEvent(
+  event: AllEvents
+): event is Event<GenericEvents, 'generic:numbers'> {
+  return event.type === 'generic:numbers'
+}
+export function isGenericStringEvent(
+  event: AllEvents
+): event is Event<GenericEvents, 'generic:string'> {
+  return event.type === 'generic:string'
+}
+export function isGenericStringsEvent(
+  event: AllEvents
+): event is Event<GenericEvents, 'generic:strings'> {
+  return event.type === 'generic:strings'
+}
+
+// --
+
+export interface BrowserEventData {
+  sid: string
+  path: string
+}
+
+export type BrowserDataPoint<T = {}> = BrowserEventData & T
+
+export type BrowserEvents = {
+  'session:start': BrowserDataPoint<SessionData>
+  'session:dnt': never
+  'session:end': BrowserDataPoint
+  'page:visit': BrowserDataPoint<PageVisitData>
+  'page:hide': BrowserDataPoint
+  'page:show': BrowserDataPoint
+}
+export type BrowserEvent = Event<BrowserEvents, keyof BrowserEvents>
+
+export function isBrowserEvent(event: AllEvents): event is BrowserEvent {
+  return (
+    isSessionStartEvent(event) ||
+    isSessionEndEvent(event) ||
+    isPageVisitEvent(event) ||
+    isPageHideEvent(event) ||
+    isPageShowEvent(event)
+  )
+}
+export function isSessionStartEvent(
+  event: AllEvents
+): event is Event<BrowserEvents, 'session:start'> {
+  return event.type === 'session:start'
+}
+export function isSessionDNTEvent(
+  event: AllEvents
+): event is Event<BrowserEvents, 'session:dnt'> {
+  return event.type === 'session:dnt'
+}
+export function isSessionEndEvent(
+  event: AllEvents
+): event is Event<BrowserEvents, 'session:end'> {
+  return event.type === 'session:end'
+}
+export function isPageVisitEvent(
+  event: AllEvents
+): event is Event<BrowserEvents, 'page:visit'> {
+  return event.type === 'page:visit'
+}
+export function isPageHideEvent(
+  event: AllEvents
+): event is Event<BrowserEvents, 'page:hide'> {
+  return event.type === 'page:hide'
+}
+export function isPageShowEvent(
+  event: AllEvents
+): event is Event<BrowserEvents, 'page:show'> {
+  return event.type === 'page:show'
+}
+
+function eventFactory<Events>() {
+  return function createEvent<K extends keyof Events>(
+    type: K,
+    data?: Events[K]
+  ): Event<Events, K> {
+    return {
+      type,
+      time: Date.now(),
+      data
+    }
+  }
+}
+
+export const createGenericEvent = eventFactory<GenericEvents>()
+export const createBrowserEvent = eventFactory<BrowserEvents>()
+
+export type EventSender = <T>(event: Event<T, keyof T>) => void
+
+export type AllEvents = GenericEvent | BrowserEvent
diff --git a/src/index.test.ts b/src/index.test.ts
index f1313cf..f0c893f 100644
--- a/src/index.test.ts
+++ b/src/index.test.ts
@@ -1,5 +1,36 @@
-import hello from './index'
+import { sessionStart, sessionEnd, pageHide, pageShow } from './session'
+import {
+  isBrowserEvent,
+  isSessionStartEvent,
+  isSessionEndEvent,
+  isPageHideEvent,
+  isPageShowEvent
+} from './events'
 
-test('testing works', () => {
-  expect(hello('World')).toEqual('Hello, World !')
+test('sessionStart', () => {
+  const event = sessionStart()
+  expect(event.type).toEqual('session:start')
+  expect(isBrowserEvent(event)).toEqual(true)
+  expect(isSessionStartEvent(event)).toEqual(true)
+})
+
+test('sessionEnd', () => {
+  const event = sessionEnd()
+  expect(event.type).toEqual('session:end')
+  expect(isBrowserEvent(event)).toEqual(true)
+  expect(isSessionEndEvent(event)).toEqual(true)
+})
+
+test('pageHide', () => {
+  const event = pageHide()
+  expect(event.type).toEqual('page:hide')
+  expect(isBrowserEvent(event)).toEqual(true)
+  expect(isPageHideEvent(event)).toEqual(true)
+})
+
+test('pageShow', () => {
+  const event = pageShow()
+  expect(event.type).toEqual('page:show')
+  expect(isBrowserEvent(event)).toEqual(true)
+  expect(isPageShowEvent(event)).toEqual(true)
 })
diff --git a/src/index.ts b/src/index.ts
index b21024d..16537cb 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1 +1,3 @@
-export default (name: string) => `Hello, ${name} !`
+export * from './events'
+export * from './session'
+export * from './navigation'
diff --git a/src/navigation.ts b/src/navigation.ts
new file mode 100644
index 0000000..6ee1afc
--- /dev/null
+++ b/src/navigation.ts
@@ -0,0 +1,24 @@
+import { createBrowserEvent, EventSender } from './events'
+import { sessionID } from './session'
+
+export interface PageVisitData {
+  from: string
+}
+
+export const setupPageVisitListeners = (send: EventSender) => {
+  let oldPath = window.location.pathname
+
+  setInterval(() => {
+    const newPath = window.location.pathname
+    if (oldPath === newPath) {
+      return
+    }
+    const event = createBrowserEvent(`page:visit`, {
+      sid: sessionID,
+      from: oldPath,
+      path: newPath
+    })
+    oldPath = newPath
+    send(event)
+  }, 500)
+}
diff --git a/src/session.ts b/src/session.ts
new file mode 100644
index 0000000..3dfe21c
--- /dev/null
+++ b/src/session.ts
@@ -0,0 +1,72 @@
+import nanoid from 'nanoid'
+import { createBrowserEvent, EventSender } from './events'
+
+export const sessionID = nanoid()
+
+export interface SessionData {
+  ua: string // user-agent
+  os: string // operating system
+  ref: string // referer
+  lang: string // language
+  tzo: number // timezone offset from UTC in minutes
+  vp: {
+    // viewport dimensions
+    w: number
+    h: number
+  }
+  lvd?: string // last visit date, ISO-8601
+}
+
+export const sessionStart = () => {
+  const event = createBrowserEvent('session:start', {
+    ua: navigator.userAgent,
+    os: navigator.platform,
+    ref: document.referrer,
+    lang: navigator.language,
+    tzo: new Date().getTimezoneOffset(),
+    vp: {
+      w: window.innerWidth,
+      h: window.innerHeight
+    },
+    lvd: window.localStorage.getItem('chiffre:last-visit-date') || undefined,
+    sid: sessionID,
+    path: window.location.pathname
+  })
+  window.localStorage.setItem(
+    'chiffre:last-visit-date',
+    new Date().toISOString().slice(0, 10) // YYYY-MM-DD
+  )
+  return event
+}
+
+export const sessionEnd = () => {
+  return createBrowserEvent('session:end', {
+    sid: sessionID,
+    path: window.location.pathname
+  })
+}
+
+export const pageHide = () => {
+  return createBrowserEvent('page:hide', {
+    sid: sessionID,
+    path: window.location.pathname
+  })
+}
+
+export const pageShow = () => {
+  return createBrowserEvent('page:show', {
+    sid: sessionID,
+    path: window.location.pathname
+  })
+}
+
+export const setupSessionListeners = (send: EventSender) => {
+  const startEvent = sessionStart()
+  window.addEventListener('beforeunload', () => {
+    send(sessionEnd())
+  })
+  window.addEventListener('visibilitychange', () => {
+    send(document.hidden ? pageHide() : pageShow())
+  })
+  send(startEvent)
+}
diff --git a/yarn.lock b/yarn.lock
index cdba3e4..6d6e959 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -516,11 +516,6 @@
   resolved "https://registry.yarnpkg.com/@types/color-name/-/color-name-1.1.1.tgz#1c1261bbeaa10a8055bbc5d8ab84b7b2afc846a0"
   integrity sha512-rr+OQyAjxze7GgWrSaJwydHStIhHq2lvY3BOC2Mj7KnzI7XK0Uw1TOOdI9lDoajEbSWLiYgoo4f1R51erQfhPQ==
 
-"@types/faker@^4.1.10":
-  version "4.1.10"
-  resolved "https://registry.yarnpkg.com/@types/faker/-/faker-4.1.10.tgz#ec31466931086122b05be719d084989ffe3d6eb6"
-  integrity sha512-Z1UXXNyxUcuu7CSeRmVizMgH7zVYiwfiTgXMnSTvsYDUnVt3dbMSpPdfG/H41IBiclgFGQJgLVdDFeinhhmWTg==
-
 "@types/istanbul-lib-coverage@*", "@types/istanbul-lib-coverage@^2.0.0", "@types/istanbul-lib-coverage@^2.0.1":
   version "2.0.1"
   resolved "https://registry.yarnpkg.com/@types/istanbul-lib-coverage/-/istanbul-lib-coverage-2.0.1.tgz#42995b446db9a48a11a07ec083499a860e9138ff"
@@ -549,7 +544,14 @@
     jest-diff "^25.1.0"
     pretty-format "^25.1.0"
 
-"@types/node@^13.9.1":
+"@types/nanoid@^2.1.0":
+  version "2.1.0"
+  resolved "https://registry.yarnpkg.com/@types/nanoid/-/nanoid-2.1.0.tgz#41edfda78986e9127d0dc14de982de766f994020"
+  integrity sha512-xdkn/oRTA0GSNPLIKZgHWqDTWZsVrieKomxJBOQUK9YDD+zfSgmwD5t4WJYra5S7XyhTw7tfvwznW+pFexaepQ==
+  dependencies:
+    "@types/node" "*"
+
+"@types/node@*", "@types/node@^13.9.1":
   version "13.9.1"
   resolved "https://registry.yarnpkg.com/@types/node/-/node-13.9.1.tgz#96f606f8cd67fb018847d9b61e93997dabdefc72"
   integrity sha512-E6M6N0blf/jiZx8Q3nb0vNaswQeEyn0XlupO+xN6DtJ6r6IT4nXrTry7zhIfYvFCl3/8Cu6WIysmUBKiqV0bqQ==
@@ -1538,11 +1540,6 @@ extsprintf@^1.2.0:
   resolved "https://registry.yarnpkg.com/extsprintf/-/extsprintf-1.4.0.tgz#e2689f8f356fad62cca65a3a91c5df5f9551692f"
   integrity sha1-4mifjzVvrWLMplo6kcXfX5VRaS8=
 
-faker@^4.1.0:
-  version "4.1.0"
-  resolved "https://registry.yarnpkg.com/faker/-/faker-4.1.0.tgz#1e45bbbecc6774b3c195fad2835109c6d748cc3f"
-  integrity sha1-HkW7vsxndLPBlfrSg1EJxtdIzD8=
-
 fast-deep-equal@^3.1.1:
   version "3.1.1"
   resolved "https://registry.yarnpkg.com/fast-deep-equal/-/fast-deep-equal-3.1.1.tgz#545145077c501491e33b15ec408c294376e94ae4"
@@ -2881,6 +2878,11 @@ ms@^2.1.1:
   resolved "https://registry.yarnpkg.com/ms/-/ms-2.1.2.tgz#d09d1f357b443f493382a8eb3ccd183872ae6009"
   integrity sha512-sGkPx+VjMtmA6MX27oA4FBFELFCZZ4S4XqeGOXCv68tT+jb3vk/RyaKWP0PTKyWtmLSM0b+adUTEvbs1PEaH2w==
 
+nanoid@^2.1.11:
+  version "2.1.11"
+  resolved "https://registry.yarnpkg.com/nanoid/-/nanoid-2.1.11.tgz#ec24b8a758d591561531b4176a01e3ab4f0f0280"
+  integrity sha512-s/snB+WGm6uwi0WjsZdaVcuf3KJXlfGl2LcxgwkEwJF0D/BWzVWAZW/XY4bFaiR7s0Jk3FPvlnepg1H1b1UwlA==
+
 nanomatch@^1.2.9:
   version "1.2.13"
   resolved "https://registry.yarnpkg.com/nanomatch/-/nanomatch-1.2.13.tgz#b87a8aa4fc0de8fe6be88895b38983ff265bd119"