To list database type the following command

mysql> show databases;
Output:

+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
+--------------------+
2 rows in set (0.00 sec)

information_schema and mysql are name of databases. To use these database and to list available tables type the following two commands:
mysql> use mysql;

Output:

Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed

Now list tables:
mysql> show tables;

Output:

+---------------------------+
| Tables_in_mysql           |
+---------------------------+
| columns_priv              |
| db                        |
| func                      |
| help_category             |
| help_keyword              |
| help_relation             |
| help_topic                |
| host                      |
| proc                      |
| procs_priv                |
| tables_priv               |
| time_zone                 |
| time_zone_leap_second     |
| time_zone_name            |
| time_zone_transition      |
| time_zone_transition_type |
| user                      |
+---------------------------+
17 rows in set (0.00 sec)