LAMP Stack
LAMP stack refers to a combination of Linux, Apache, MySQL, and PHP. It serves as a foundation for buidling and running web applications.

LAN
LAN (Local Area Network) enerally refers to small home/office networks. See WAN for contrast.

Linux
Open Source operating system. Different distributions (variants) include RedHat, CentOS, SuSE, Debian, Ubuntu, and openSuSe.

Log Files
Refers to the records that are kept by applications and servers to store information on access, security alerts, and more. Users often want to monitor log files for important info (e.g security alerts).

Logstash
Logstash is a tool for managing events and logs. It is used to collect logs, parse log data, and store them for later use in searches, etc. It is the ’L’ in the ELK stack and is part of Nagios Log Server.