add answers to aws-cloud-practitioner.md
diff --git a/certificates/aws-cloud-practitioner.md b/certificates/aws-cloud-practitioner.md
index 6a77583cd..e7a0b1b21 100644
--- a/certificates/aws-cloud-practitioner.md
+++ b/certificates/aws-cloud-practitioner.md
@@ -400,8 +400,8 @@ Learn more [here](https://aws.amazon.com/snowmobile)
 <details>
 <summary>What is IAM? What are some of its features?</summary><br><b>
 
+IAM stands for Identity and Access Management, and is used for managing users, groups, access policies & roles
 Full explanation is [here](https://aws.amazon.com/iam)
-In short: it's used for managing users, groups, access policies & roles
 </b></details>
 
 <details>
@@ -570,7 +570,7 @@ Read more about it [here](https://aws.amazon.com/sns)
 <details>
 <summary>What is the shared responsibility model? What AWS is responsible for and what the user is responsible for based on the shared responsibility model?</summary><br><b>
 
-The shared responsibility model defines what the customer is responsible for and what AWS is responsible for.
+The shared responsibility model defines what the customer is responsible for and what AWS is responsible for. For example, AWS is responsible for security "of" the cloud, while the customer is responsible for security "in" the cloud.
 
 More on the shared responsibility model [here](https://aws.amazon.com/compliance/shared-responsibility-model)
 </b></details>
@@ -611,6 +611,8 @@ Learn more [here](https://aws.amazon.com/inspector)
 
 <details>
 <summary>What is AWS Guarduty?</summary><br><b>
+
+Guarduty is a threat detection service that monitors your AWS accounts to help detect and mitigate malicious activity
 </b></details>
 
 <details>
@@ -621,6 +623,8 @@ AWS definition: "AWS Shield is a managed Distributed Denial of Service (DDoS) pr
 
 <details>
 <summary>What is AWS WAF? Give an example of how it can used and describe what resources or services you can use it with</summary><br><b>
+
+An AWS Web Application Firewall (WAF) can filter out unwanted web traffic (bots), and protect against attacks like SQL injection and cross-site scripting. One service you could use it with would be Amazon CloudFront, a CDN service, to block attacks before they reach your origin servers
 </b></details>
 
 <details>
@@ -697,6 +701,11 @@ Learn more [here](https://aws.amazon.com/certificate-manager)
 
 <details>
 <summary>What is AWS RDS?</summary><br><b>
+
+Amazon Relational Database Service (RDS) is a service for setting up  and managing resizable, cost-efficient relational databases
+resource
+
+Learn more [here](https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Welcome.html)
 </b></details>
 
 <details>
@@ -730,7 +739,7 @@ Learn more [here](https://aws.amazon.com/dynamodb/dax)
 <details>
 <summary>What is AWS Redshift and how is it different than RDS?</summary><br><b>
 
-cloud data warehouse
+AWS Redshift is a cloud data warehousing service that is geared towards handling massive amounts of data (think petabytes) and being able to execute complex queries. In contrast, Amazon RDS is best suited for things like web applications requiring simple queries with more frequent transactions, and on a smaller scale.
 </b></details>
 
 <details>
@@ -815,7 +824,7 @@ CloudFormation
 <details>
 <summary>Which service would you use for building a website or web application?</summary><br><b>
 
-Lightsail
+Lightsail or Elastic Beanstalk
 </b></details>
 
 <details>

Added some answers to the aws-cloud-practitioner.md. 
I answered a few unanswered questions, and I also made a few modifications to existing answers.

Namely,
a) The answer to the question "What is IAM?" was modified to include what the acronym stands for (Identity and Access Management)
b) The answer to the question "what is AWS Redshift and how is it different than RDS" only had a partial answer, and didn't answer how it was different than RDS
c) The answer to the question "which service would you use for building a website or web application" only listed Lightsail, while Elastic Beanstalk is a common alternative depending on project requirements.
d) The answer to the Shared Responsibility Model was made more specific by including the associated key phrase