Add files:
7z a -t7z archive.7z *.txt

Delete files:
7z d archive.7z *.bak -r 

Extract files:
7z e archive.7z

Extract files - preserves the full paths:
7z x archive.7z

List files:
7z l archive.7z

Update files:
7z u archive.7z *.txt

Switch t type

Here I show how you can specify the precise archive type you want to create. Note that you can specify any filename you want for any type. But some extensions are recommended.

Switch -t7z: Format: 7Z Example filename: archive.7z (default option)

Switch -tgzip: Format: GZIP Example filenames: archive.gzip, archive.gz

Switch -tzip: Format: ZIP Example filename: archive.zip (compatible)

Switch -tbzip2: Format: BZIP2 Example filename: archive.bzip2

Switch -ttar: Format: TAR Example filename: tarball.tar (UNIX and Linux)

Switch -tiso: Format: ISO Example filename: image.iso

Switch -tudf: Format: UDF Example filename: disk.udf