USB is an abbreviation for Universal Serial Bus. USB is an industry-standard for short-distance communication, such as between a computer and a keyboard, a computer and a mouse, a monitor and a laptop, a printer and a computer, and so on. USB devices are now widespread due to the ease with which they can be configured and connected. The USB system has two types of ports: downstream and upstream. In this article, I will explain the Downstream and Upstream ports, as well as their applications in the monitor.
Before we get into those ports, there's one thing you should know. HDMI and RJ45 ports only send data to their respective devices, whereas USB ports can carry both power and data. Due to which USB gadgets do not need an extra cable for power.
Upstream ports receive power and data from the host. The host in the case of a standalone monitor is a desktop PC / laptop, and a USB port is present in the standalone monitor. If a desktop PC or laptop is a Host, it usually has a Type A Connector, and an Upstream Port in a standalone monitor has a Type B Connector (ie. an upstream connector). These are linked using the cable below, which has both Type A and Type B ports.
As power and data are received by the monitor from Desktop PC / laptop so, the content of the laptop and desktop will be visible on the monitor. Therefore, the Upstream port is present in the monitor. This doesn't mean that the monitor does not require power. Monitors need extra AC mains cable to plug into an outlet. But if you consider thunderbolt and USB Type C port-based monitors which may not need extra power cable because they can drive enough power to an LCD monitor.
Some monitors have USB UP written on them, which represents the USB Upstream port and USB IN represents the USB Downstream port.
Upstream and Downstream is the USB hub feature of the monitor. It eliminates the need to run multiple cables from your monitor desk to your computer. Multiple cables connect to your monitor, and a single USB cable connects to your computer.
Downstream Port sends data and power to the devices like keyboard, mouse, standalone monitor, etc. In monitor there is a downstream port as well, if you want to connect peripherals like a mouse, keyboard, speaker, flash drive, etc then you can connect to the Downstream port present in Monitor. Downstream Port sends power and data to those external peripheral.USB supplies power at 5 V to power USB downstream devices.
In most of the standalone hp and dell monitors, there is both upstream and downstream port available. The upstream port receives data and power from the host (generally desktop PCs or laptops). In these types of monitor, there should be a hub in between which connects the upstream port and downstream port. So, commonly there will only be one Upstream port and multiple Downstream ports in the monitor.
My Recommendation: If you want to connect a monitor for viewing the computer's video display then the USB port with Type A and Type B are not good. If the data port is Type C and Thunderbolt type then it is ok for video. Generally, prefer port for video is HDMI and DP.