DVI-D is the digital-only DVI connector that brought cleaner, higher-resolution video to older flat panels and PCs. Today it still works well for legacy monitors and basic desktop setups, but HDMI and DisplayPort are better choices for audio, higher resolutions, and modern features.
"HD Ready" originally meant a TV could accept HD signals (720p/1080i) but didn't guarantee a native 1080p panel or built-in tuner. Today, look for native resolution, HDMI version, HDR, and HDCP support rather than legacy badges.
DVI and HDMI use compatible digital video signaling, so passive DVI↔HDMI cables pass video reliably. HDMI adds audio and modern AV features (ARC/eARC, CEC, higher bandwidths) that DVI lacks. Use passive adapters for video-only needs; use active converters or HDMI gear when you need audio or advanced HDMI features.