add intro to wallet canister (dfinity#318)

* add intro to wallet canister * Update modules/developers-guide/pages/concepts/canisters-intro.adoc
liling0509 · Feb 8, 2021 · a5a3497 · a5a3497
1 parent b28cad1
commit a5a3497
Showing 1 changed file with 7 additions and 7 deletions.
diff --git a/modules/developers-guide/pages/concepts/canisters-intro.adoc b/modules/developers-guide/pages/concepts/canisters-intro.adoc
@@ -125,18 +125,18 @@ A single user can have multiple public-private key pairs for accessing canisters
 == Resource consumption and cycles
 
 In general, all canisters consume resources in the form of CPU cycles for execution, bandwidth for routing messages, and memory for persisted data.
-Canisters maintain an account balance to pay for the cost of communication, computation, and storage their applications consume. 
-The cost of computation is referred to as *cycles*.
+Canisters maintain an account balance of *cycles* to pay for the cost of communication, computation, and storage that their applications consume. 
 
-Cycles reflects the real costs of operations including resources such physical hardware, rack space, energy,storage devices, and bandwidth. 
-In simple terms, a *unit of cycles* represents the cost of executing a single WebAssembly instruction. 
+Cycles are intended to reflect the real cost of operations including physical hardware, rack space, energy, storage devices, and bandwidth in a stable or deflationary way so that the cost of program execution remains the same or decreases with operational efficiency. 
 
 * Programs must be able to pay for complete execution (all or nothing), but the cost associated with a unit of cycles will make efficient programs cost-effective.
-* By setting limits on how many cycles a canister can consume, the platform can prevent malicious code from draining resources
+* By setting limits on how many cycles a canister can consume, the platform can prevent malicious code from draining resources.
 
 The relative stability of operational costs makes it easier to predict the cycles required to process, for example, a million messages.
 
-NOTE: When you deploy canisters locally or to an {IC} test network, there’s no cost associated with program execution. However, it is possible that in calculating the operations to be performed, executing a program might result in an “out of cycles” exception because the operations would exceed a predefined threshold. 
+The cycles available for program execution are held in a **wallet canister**. For local deployment, wallet canisters are automatically created and issued cycles. To deploy your application on the {IC} network running on external nodes and subnets, however, you'll need to provide a principal and be issued a wallet canister identifier.
+
+NOTE: When you deploy canisters locally or to an {IC} test network, program execution consumes cycles but there are no funds associated with those cycles. However, it is possible that in calculating the operations to be performed, executing a program might result in an “out of cycles” exception because the operations would exceed a predefined threshold. 
 If you see this exception in testing, you can temporarily configure a higher cycles limit by setting a command-line option. 
 
 == Want to learn more?
@@ -147,4 +147,4 @@ If you are looking for more information about canisters, check out the following
 
 * link:https://www.youtube.com/watch?v=60uHQfoA8D[What is the DFINITY Canister SDK? (video)]
 
-* link:https://www.youtube.com/watch?v=yqIoiyuG[Deploying your first application (video)]
+* link:https://www.youtube.com/watch?v=yqIoiyuG[Deploying your first application (video)]