给定一篇英文专业文章，将其中的语言和表达方式转化为普通人也能理解的语言。



Network security is a critical issue in modern computer systems. There are a number of strategies that can be employed to ensure that networks remain secure. One commonly used strategy is to limit access to the network to authorized users only. Another strategy is to use encryption to protect transmitted data. Still another strategy is to employ a firewall to monitor and control network traffic.
Keeping computer networks secure is very important these days. People use different ways to make sure their networks are safe. One way is to only let authorized people use the network. Another way is to use codes to protect information that's sent through the network. Another way is to use something called a firewall to watch over and manage the things that go through the network.