diff --git a/content/notes/16-cloud-security.md b/content/notes/16-cloud-security.md
index 9b550b2c5..a2f027331 100644
--- a/content/notes/16-cloud-security.md
+++ b/content/notes/16-cloud-security.md
@@ -6,4 +6,94 @@ tags:
 - lecture
 ---
 
-# what is cloud
\ No newline at end of file
+- what is cloud computing
+- what is service virtualisation
+- security issues
+
+# what is cloud
+- largely a marketing term
+- vague - doesn't mean much
+- slowly replacing the word 'web'
+
+implies
+- large cluster of networked servers acting as hosts
+	- usually virtualised
+- large number of users
+- complexity of infrastructure hidden from devs
+	- and users
+
+## cloud platforms
+### SaaS
+- provider has an actual product
+	- they host it (or delegate the hosting)
+	- customer doesn't need to host anything
+- thin client
+	- usually web based
+	- maybe also mobile app
+
+examples
+- customer realtions (salesforce)
+- accounting (xero)
+- PoS (vend)
+- dropbox, gmail, google docs
+
+### PaaS
+- provides a solution stack
+	- tools, environment, services, libraries to run a system
+		- storage services / libaries / tools
+		- email libraries
+		- web app libraries
+		- admin tools: deployment, scaling, logs, billing, quotas etc
+- extensible
+	- devs can add their own libraries
+
+examples
+- google app engine
+- elastic beanstalk
+- azure cloud services
+- heroku
+
+### IaaS
+- virtual hosting
+	- allows custome to run own VM
+		- linux or wiindows server
+		- customer can install whatever on the VM
+		- barebones or canned VM images are available
+		- customer can provide own images
+- virtual networking
+	- public facing IP addresses mapped to virtual network interfaces for load balancing, and fault tolerance
+- virtual storage
+	- file storage
+	- exampkes
+		- amazon S3
+		- google cloud storage
+		- azure storage
+	- hot storage for frequently access data
+		- higher performance, higher cost
+	- cold for infrequent access
+
+## primary selling points
+- agility/elasticity
+- reduced cost
+	- multitenancy
+	- economies of scale
+	- usage based billing
+- reliability
+	- massive redundancy
+- low capital expenditure
+- greener
+	- low power hardware, virtualisation, centralisation of cooling, environmental cooling, sharing of resources
+
+## potential problems
+- Saas
+	- need to train staff
+	- importing and exporting data may be difficult
+	- dependent on provider health
+	- vulnerable to price changes
+	- provider may be aquired by another company with different goals
+- Paas
+	- use of common APIs libraries and services mitigate the lock-in problem
+	- avoid using vendor specific APIs, or wrap them with facades
+- IaaS
+	- mitigated by sticking to the standard services (MySQL & nginx for example) and standard libs
+	- avoid vendor specific interfaces to proprietary services
\ No newline at end of file